{"attribution":{"source":"legal.exploreworldai.com","canonical":"https://legal.exploreworldai.com/api/public/v1/judgment-text?id=us:scotus-23-1209-2026-05-21","cite_as":"NovaCopilot, legal.exploreworldai.com (https://legal.exploreworldai.com/api/public/v1/judgment-text?id=us:scotus-23-1209-2026-05-21)","license":"https://legal.exploreworldai.com/revision","version":"legal-2026-10-14","fingerprint":"ewai:us:88b5b2","proof":"sha256:25a64b775c70475f46e5470ac46bc79d9433e3fbc7c65e876f8fba589e87fb61","jurisdiction":"us","lang":"en","publisher":"NovaCopilot by ExploreWorld Legal","terms":"https://legal.exploreworldai.com/om"},"brand_source":"Source: NovaCopilot","item":{"schema_version":"1.0.0","id":"us:scotus-23-1209-2026-05-21","jurisdiction":"us","lang":"en","brand_source":"Source: NovaCopilot","brand":{"product":"NovaCopilot","platform":"ExploreWorldAI","infrastructure":"ExploreWorld Legal","infrastructure_url":"legal.exploreworldai.com","legal_entity":"Valkiv Ventures AB","permanent_url":"https://legal.exploreworldai.com/novacopilot","source":"Source: NovaCopilot","powered_by":"Powered by NovaCopilot","license":"https://legal.exploreworldai.com/licensvillkor"},"sections":[{"title":"Front matter","paragraphs":["para_1","para_2","para_3","para_4","para_5","para_6","para_7","para_8","para_9","para_10","para_11","para_12","para_13","para_14","para_15","para_16","para_17","para_18","para_19","para_20","para_21","para_22","para_23","para_24","para_25","para_26","para_27","para_28","para_29","para_30","para_31","para_32","para_33","para_34","para_35","para_36","para_37","para_38","para_39","para_40","para_41","para_42","para_43","para_44","para_45","para_46","para_47","para_48","para_49","para_50","para_51","para_52","para_53","para_54","para_55","para_56","para_57","para_58","para_59","para_60","para_61","para_62","para_63","para_64","para_65","para_66","para_67","para_68","para_69","para_70","para_71","para_72","para_73","para_74","para_75","para_76","para_77","para_78","para_79","para_80","para_81","para_82","para_83","para_84","para_85","para_86","para_87","para_88","para_89","para_90","para_91","para_92","para_93","para_94","para_95","para_96","para_97","para_98","para_99","para_100","para_101","para_102","para_103","para_104","para_105","para_106","para_107","para_108","para_109","para_110","para_111","para_112","para_113","para_114","para_115","para_116","para_117","para_118","para_119","para_120","para_121","para_122","para_123","para_124","para_125","para_126","para_127","para_128","para_129","para_130","para_131","para_132","para_133","para_134","para_135","para_136","para_137","para_138","para_139","para_140","para_141","para_142","para_143","para_144","para_145","para_146","para_147","para_148","para_149","para_150","para_151","para_152","para_153","para_154","para_155","para_156","para_157","para_158","para_159","para_160","para_161","para_162","para_163","para_164","para_165","para_166","para_167","para_168","para_169","para_170","para_171","para_172","para_173","para_174","para_175","para_176","para_177","para_178","para_179","para_180","para_181","para_182","para_183","para_184","para_185","para_186","para_187","para_188","para_189","para_190","para_191","para_192","para_193","para_194","para_195","para_196","para_197","para_198","para_199","para_200","para_201","para_202","para_203","para_204","para_205","para_206","para_207","para_208","para_209","para_210","para_211","para_212","para_213","para_214","para_215","para_216","para_217","para_218","para_219","para_220","para_221","para_222","para_223","para_224","para_225","para_226","para_227","para_228","para_229","para_230","para_231","para_232","para_233","para_234","para_235","para_236","para_237","para_238","para_239","para_240","para_241","para_242","para_243","para_244","para_245","para_246","para_247","para_248","para_249","para_250","para_251","para_252","para_253","para_254","para_255","para_256","para_257","para_258","para_259","para_260","para_261","para_262","para_263","para_264","para_265","para_266","para_267","para_268","para_269","para_270","para_271","para_272","para_273","para_274","para_275","para_276","para_277","para_278","para_279","para_280","para_281","para_282","para_283","para_284","para_285","para_286","para_287","para_288","para_289","para_290","para_291","para_292","para_293","para_294","para_295","para_296","para_297","para_298","para_299","para_300","para_301","para_302","para_303","para_304","para_305","para_306","para_307","para_308","para_309","para_310","para_311","para_312","para_313","para_314","para_315","para_316","para_317","para_318","para_319","para_320","para_321","para_322","para_323","para_324","para_325","para_326","para_327","para_328","para_329","para_330","para_331","para_332","para_333","para_334","para_335","para_336","para_337","para_338","para_339","para_340","para_341","para_342","para_343","para_344","para_345","para_346","para_347","para_348","para_349","para_350","para_351","para_352","para_353","para_354","para_355","para_356","para_357","para_358","para_359","para_360","para_361","para_362","para_363","para_364","para_365","para_366","para_367","para_368","para_369","para_370","para_371","para_372","para_373","para_374","para_375","para_376","para_377","para_378","para_379","para_380","para_381","para_382","para_383","para_384","para_385","para_386","para_387","para_388","para_389","para_390","para_391","para_392","para_393","para_394","para_395","para_396","para_397","para_398","para_399","para_400","para_401","para_402","para_403","para_404","para_405","para_406","para_407","para_408","para_409","para_410","para_411","para_412","para_413","para_414","para_415","para_416","para_417","para_418","para_419","para_420","para_421","para_422","para_423","para_424","para_425","para_426","para_427","para_428","para_429","para_430","para_431","para_432","para_433","para_434","para_435","para_436","para_437","para_438","para_439","para_440","para_441","para_442","para_443","para_444","para_445","para_446","para_447","para_448","para_449","para_450","para_451","para_452","para_453","para_454","para_455","para_456","para_457","para_458","para_459","para_460","para_461","para_462","para_463","para_464","para_465","para_466","para_467","para_468","para_469","para_470","para_471","para_472","para_473","para_474","para_475","para_476","para_477","para_478","para_479","para_480","para_481","para_482","para_483","para_484","para_485","para_486","para_487","para_488","para_489","para_490","para_491","para_492","para_493","para_494","para_495","para_496","para_497","para_498","para_499","para_500","para_501","para_502","para_503","para_504","para_505","para_506","para_507","para_508","para_509","para_510","para_511","para_512","para_513","para_514","para_515","para_516","para_517","para_518","para_519","para_520","para_521","para_522","para_523","para_524","para_525","para_526","para_527"],"kind":"front_matter"}],"paragraphs":[{"text":"1(Slip Opinion) OCTOBER TERM, 2025","paragraph_id":"para_1"},{"text":"Syllabus","paragraph_id":"para_2"},{"text":"NOTE: Where it is feasible, a syllabus (headnote) will be released, as is","paragraph_id":"para_3"},{"text":"being done in connection with this case, at the time the opinion is issued.","paragraph_id":"para_4"},{"text":"The syllabus constitutes no part of the opinion of the Court but has been","paragraph_id":"para_5"},{"text":"prepared by the Reporter of Decisions for the convenience of the reader.","paragraph_id":"para_6"},{"text":"See United States v. Detroit Timber & Lumber Co., 200 U. S. 321, 337.","paragraph_id":"para_7"},{"text":"SUPREME COURT OF THE UNITED STATES","paragraph_id":"para_8"},{"text":"Syllabus","paragraph_id":"para_9"},{"text":"M & K EMPLOYEE SOLUTIONS, LLC, ET AL. v.","paragraph_id":"para_10"},{"text":"TRUSTEES OF THE IAM NATIONAL PENSION FUND","paragraph_id":"para_11"},{"text":"CERTIORARI TO THE UNITED STATES COURT OF APPEALS FOR","paragraph_id":"para_12"},{"text":"THE DISTRICT OF COLUMBIA CIRCUIT","paragraph_id":"para_13"},{"text":"No. 23–1209. Argued January 20, 2026—Decided May 21, 2026","paragraph_id":"para_14"},{"text":"Pursuant to the Employee Retirement Income Security Act of 1974","paragraph_id":"para_15"},{"text":"(ERISA), as amended, an employer that stops participating in an un-","paragraph_id":"para_16"},{"text":"derfunded Multiemployer Pension Plan (MPP), must pay the plan","paragraph_id":"para_17"},{"text":"“withdrawal liability,” i.e., the employer’s share of the plan’s unfunded","paragraph_id":"para_18"},{"text":"vested benefits (UVBs). See 29 U. S. C. §1391. Withdrawal liability is","paragraph_id":"para_19"},{"text":"calculated based on the plan’s UVBs “as of ” the statutory measure-","paragraph_id":"para_20"},{"text":"ment date—the last day of the plan year preceding the employer’s","paragraph_id":"para_21"},{"text":"withdrawal. §§1391(b)(2)(E)(i), (c)(2)(C)(i), (3)(A), (4)(A). Determining","paragraph_id":"para_22"},{"text":"the value of a plan’s UVBs depends upon both hard data (such as the","paragraph_id":"para_23"},{"text":"number of beneficiaries and the value of the plan’s assets) and a vari-","paragraph_id":"para_24"},{"text":"ety of actuarial predictions about the future. One key actuarial as-","paragraph_id":"para_25"},{"text":"sumption is the discount rate, which is the interest rate “used to dis-","paragraph_id":"para_26"},{"text":"count future benefit payments to their present value.” 87 Fed. Reg.","paragraph_id":"para_27"},{"text":"62317.","paragraph_id":"para_28"},{"text":"Petitioners are four employers who withdrew from the IAM National","paragraph_id":"para_29"},{"text":"Pension Fund (Fund)—an underfunded MPP—between April and De-","paragraph_id":"para_30"},{"text":"cember 2018. The Fund assessed each employer’s withdrawal liability","paragraph_id":"para_31"},{"text":"“as of ” December 31, 2017 (the measurement date). In making this","paragraph_id":"para_32"},{"text":"calculation, the Fund applied a discount rate of 6.50%, which it had","paragraph_id":"para_33"},{"text":"adopted with its actuarial firm in January 2018. The Fund had previ-","paragraph_id":"para_34"},{"text":"ously used a discount rate of 7.50% to value its UVBs. Petitioners each","paragraph_id":"para_35"},{"text":"initiated arbitrations challenging their assessments. In each case, the","paragraph_id":"para_36"},{"text":"arbitrators determined that the assessments were erroneous because","paragraph_id":"para_37"},{"text":"the Fund had applied actuarial assumptions adopted after the meas-","paragraph_id":"para_38"},{"text":"urement date. The arbitrators instead required the Fund to use the","paragraph_id":"para_39"},{"text":"2 M & K EMPLOYEE SOLUTIONS, LLC v. TRUSTEES OF","paragraph_id":"para_40"},{"text":"IAM NAT. PENSION FUND","paragraph_id":"para_41"},{"text":"Syllabus","paragraph_id":"para_42"},{"text":"actuarial assumptions that were “in effect” on the measurement date—","paragraph_id":"para_43"},{"text":"i.e., the 7.50% discount rate. App. 293. The Fund sought review in","paragraph_id":"para_44"},{"text":"Federal District Court. The courts disagreed with the arbitrators and","paragraph_id":"para_45"},{"text":"held that actuaries could use assumptions adopted after the measure-","paragraph_id":"para_46"},{"text":"ment date. The D.C. Circuit affirmed in a consolidated appeal. Its","paragraph_id":"para_47"},{"text":"decision conflicted with a decision of the Second Circuit, and this Court","paragraph_id":"para_48"},{"text":"granted certiorari to resolve when actuarial assumptions may be se-","paragraph_id":"para_49"},{"text":"lected for purposes of calculating withdrawal liability.","paragraph_id":"para_50"},{"text":"Held: The provisions of ERISA governing the calculation of withdrawal","paragraph_id":"para_51"},{"text":"liability—§§1391 and 1393—do not require the actuarial assumptions","paragraph_id":"para_52"},{"text":"underlying that calculation to be selected on or before the measure-","paragraph_id":"para_53"},{"text":"ment date. Pp. 6–11.","paragraph_id":"para_54"},{"text":"(a) Section 1391 requires withdrawal liability to be calculated based","paragraph_id":"para_55"},{"text":"on the value of a plan’s UVBs “as of ” the measurement date. Petition-","paragraph_id":"para_56"},{"text":"ers contend that §1391’s “as of ” language establishes a deadline for the","paragraph_id":"para_57"},{"text":"selection of actuarial assumptions. But §1391 sets no such deadline.","paragraph_id":"para_58"},{"text":"The term “as of ” is understood “to assign an event to one time and the","paragraph_id":"para_59"},{"text":"recognition of it to another.” W. Follett, Modern American Usage 41.","paragraph_id":"para_60"},{"text":"Section 1391’s “as of ” language thus means that the hard data that","paragraph_id":"para_61"},{"text":"feeds the UVB calculation must be fixed on the measurement date, but","paragraph_id":"para_62"},{"text":"the calculation itself can be performed after that date. Actuarial as-","paragraph_id":"para_63"},{"text":"sumptions are not observable facts about the plan; instead, they are","paragraph_id":"para_64"},{"text":"predictive judgments used as tools to calculate UVBs. Accordingly,","paragraph_id":"para_65"},{"text":"while §1391’s “as of ” requirement sets the reference point for factual","paragraph_id":"para_66"},{"text":"inputs, it has no bearing on when actuaries must select their assump-","paragraph_id":"para_67"},{"text":"tions. Pp. 6–8.","paragraph_id":"para_68"},{"text":"(b) Section 1393, which governs the use of actuarial assumptions for","paragraph_id":"para_69"},{"text":"assessing withdrawal liability, states that the assumptions must be","paragraph_id":"para_70"},{"text":"“reasonable,” “tak[e] into account the experience of the plan and rea-","paragraph_id":"para_71"},{"text":"sonable expectations,” and “offer the actuary’s best estimate of antici-","paragraph_id":"para_72"},{"text":"pated experience under the plan.” §1393(a)(1). Section 1393 provides","paragraph_id":"para_73"},{"text":"no deadline by which actuaries must select their assumptions, and the","paragraph_id":"para_74"},{"text":"Court does not generally read limitations into statutes that do not ap-","paragraph_id":"para_75"},{"text":"pear in their text. Romag Fasteners, Inc. v. Fossil Group, Inc., 590","paragraph_id":"para_76"},{"text":"U. S. 212, 215. Indeed, because Congress included a deadline for the","paragraph_id":"para_77"},{"text":"selection of actuarial assumptions in a different section of the statute,","paragraph_id":"para_78"},{"text":"but imposed no similar limit in §1393, the Court presumes that the","paragraph_id":"para_79"},{"text":"omission in §1393 is intentional. See Russello v. United States, 464","paragraph_id":"para_80"},{"text":"U. S. 16, 23. Moreover, §1393’s instruction that actuarial assumptions","paragraph_id":"para_81"},{"text":"reflect the actuary’s “best estimate,” §1393(a)(1), supports the conclu-","paragraph_id":"para_82"},{"text":"sion that actuaries can select their assumptions after the measure-","paragraph_id":"para_83"},{"text":"ment date. Requiring actuaries to use assumptions selected before the","paragraph_id":"para_84"},{"text":"measurement date could prevent them from relying on the most up-to-","paragraph_id":"para_85"},{"text":"date data when selecting their assumptions, resulting in assumptions","paragraph_id":"para_86"},{"text":"3Cite as: 608 U. S. ___ (2026)","paragraph_id":"para_87"},{"text":"Syllabus","paragraph_id":"para_88"},{"text":"that do not reflect their “best estimate.” Pp. 8–10.","paragraph_id":"para_89"},{"text":"(c) Petitioners’ remaining arguments do not overcome the absence of","paragraph_id":"para_90"},{"text":"a textual deadline for adopting actuarial assumptions. First, petition-","paragraph_id":"para_91"},{"text":"ers point to a different provision of ERISA that prohibits plans from","paragraph_id":"para_92"},{"text":"applying any new “plan rule or amendment” to an employer’s with-","paragraph_id":"para_93"},{"text":"drawal liability if the rule or amendment is adopted after the employer","paragraph_id":"para_94"},{"text":"withdraws. §1394(a). But the retroactivity limits in §1394 concededly","paragraph_id":"para_95"},{"text":"do not apply to actuarial assumptions. Congress chose not to enact a","paragraph_id":"para_96"},{"text":"similar antiretroactivity rule in §1393, and inferring one would over-","paragraph_id":"para_97"},{"text":"ride Congress’s choice.","paragraph_id":"para_98"},{"text":"Petitioners fall back on a policy argument, contending that allowing","paragraph_id":"para_99"},{"text":"plans to adopt actuarial assumptions after the measurement date will","paragraph_id":"para_100"},{"text":"invite manipulation, enabling plans and their actuaries to retroac-","paragraph_id":"para_101"},{"text":"tively select assumptions in order to increase withdrawing employers’","paragraph_id":"para_102"},{"text":"liability. But petitioners’ proposed rule does not address these con-","paragraph_id":"para_103"},{"text":"cerns, and in any event, “policy concerns cannot trump the best inter-","paragraph_id":"para_104"},{"text":"pretation of the statutory text.” Patel v. Garland, 596 U. S. 328, 346.","paragraph_id":"para_105"},{"text":"Congress chose which limits to impose on the selection of actuarial as-","paragraph_id":"para_106"},{"text":"sumptions, and it is not the role of the Court to supplant Congress’s","paragraph_id":"para_107"},{"text":"choices. Pp. 10–11.","paragraph_id":"para_108"},{"text":"92 F. 4th 316, affirmed.","paragraph_id":"para_109"},{"text":"JACKSON, J., delivered the opinion for a unanimous Court.","paragraph_id":"para_110"},{"text":"_________________","paragraph_id":"para_111"},{"text":"_________________","paragraph_id":"para_112"},{"text":"1Cite as: 608 U. S. ____ (2026)","paragraph_id":"para_113"},{"text":"Opinion of the Court","paragraph_id":"para_114"},{"text":"NOTICE: This opinion is subject to formal revision before publication in the","paragraph_id":"para_115"},{"text":"United States Reports. Readers are requested to notify the Reporter of","paragraph_id":"para_116"},{"text":"Decisions, Supreme Court of the United States, Washington, D. C. 20543,","paragraph_id":"para_117"},{"text":"pio@supremecourt.gov, of any typographical or other formal errors.","paragraph_id":"para_118"},{"text":"SUPREME COURT OF THE UNITED STATES","paragraph_id":"para_119"},{"text":"No. 23–1209","paragraph_id":"para_120"},{"text":"M & K EMPLOYEE SOLUTIONS, LLC, ET AL.,","paragraph_id":"para_121"},{"text":"PETITIONERS v. TRUSTEES OF THE IAM","paragraph_id":"para_122"},{"text":"NATIONAL PENSION FUND","paragraph_id":"para_123"},{"text":"ON WRIT OF CERTIORARI TO THE UNITED STATES COURT OF","paragraph_id":"para_124"},{"text":"APPEALS FOR THE DISTRICT OF COLUMBIA CIRCUIT","paragraph_id":"para_125"},{"text":"[May 21, 2026]","paragraph_id":"para_126"},{"text":"JUSTICE JACKSON delivered the opinion of the Court.","paragraph_id":"para_127"},{"text":"An employer that stops participating in an underfunded","paragraph_id":"para_128"},{"text":"Multiemployer Pension Plan must pay the plan “with-","paragraph_id":"para_129"},{"text":"drawal liability”—i.e., its share of the plan’s unfunded","paragraph_id":"para_130"},{"text":"vested benefits. Calculating the unfunded vested benefits","paragraph_id":"para_131"},{"text":"is a complicated endeavor because the plan’s actuary must","paragraph_id":"para_132"},{"text":"predict the value of the plan’s future assets and obligations.","paragraph_id":"para_133"},{"text":"To do so, the actuary makes certain assumptions about, for","paragraph_id":"para_134"},{"text":"example, retirees’ life expectancies and the anticipated","paragraph_id":"para_135"},{"text":"growth rate of the plan’s investments. By statute, an em-","paragraph_id":"para_136"},{"text":"ployer’s withdrawal liability is based on the value of the","paragraph_id":"para_137"},{"text":"plan’s unfunded vested benefits “as of ” the last day of the","paragraph_id":"para_138"},{"text":"plan year preceding the employer’s withdrawal, also known","paragraph_id":"para_139"},{"text":"as the measurement date. 29 U. S. C. §1391.","paragraph_id":"para_140"},{"text":"The question presented in this case is whether the “as of ”","paragraph_id":"para_141"},{"text":"language sets the measurement date as the deadline by","paragraph_id":"para_142"},{"text":"which actuaries must select the assumptions that underlie","paragraph_id":"para_143"},{"text":"the withdrawal-liability calculation. The Court of Appeals","paragraph_id":"para_144"},{"text":"for the D. C. Circuit held that it does not, concluding that","paragraph_id":"para_145"},{"text":"actuaries may select their assumptions after the measure-","paragraph_id":"para_146"},{"text":"ment date. We agree. The statute governing the selection","paragraph_id":"para_147"},{"text":"2 M & K EMPLOYEE SOLUTIONS, LLC v. TRUSTEES OF","paragraph_id":"para_148"},{"text":"IAM NAT. PENSION FUND","paragraph_id":"para_149"},{"text":"Opinion of the Court","paragraph_id":"para_150"},{"text":"and use of actuarial assumptions in the withdrawal-liabil-","paragraph_id":"para_151"},{"text":"ity context contains no requirement that actuaries use as-","paragraph_id":"para_152"},{"text":"sumptions adopted prior to the measurement date.","paragraph_id":"para_153"},{"text":"I","paragraph_id":"para_154"},{"text":"A","paragraph_id":"para_155"},{"text":"The Employee Retirement Income Security Act of 1974","paragraph_id":"para_156"},{"text":"(ERISA) provides “comprehensive regulation for private","paragraph_id":"para_157"},{"text":"pension plans.” Connolly v. Pension Benefit Guaranty Cor-","paragraph_id":"para_158"},{"text":"poration, 475 U. S. 211, 214 (1986). One type of pension","paragraph_id":"para_159"},{"text":"plan that ERISA regulates is a Multiemployer Pension Plan","paragraph_id":"para_160"},{"text":"(MPP). An MPP is a plan “to which more than one employer","paragraph_id":"para_161"},{"text":"contributes” and is “maintained to fulfill the terms of collec-","paragraph_id":"para_162"},{"text":"tive-bargaining agreements.” Concrete Pipe & Products of","paragraph_id":"para_163"},{"text":"Cal., Inc. v. Construction Laborers Pension Trust for South-","paragraph_id":"para_164"},{"text":"ern Cal., 508 U. S. 602, 605 (1993); see 29 U. S. C.","paragraph_id":"para_165"},{"text":"§1002(37).","paragraph_id":"para_166"},{"text":"As amended by the Multiemployer Pension Plan Amend-","paragraph_id":"para_167"},{"text":"ments Act of 1980, ERISA requires employers that with-","paragraph_id":"para_168"},{"text":"draw from an underfunded MPP to pay “withdrawal liabil-","paragraph_id":"para_169"},{"text":"ity.” §1381(a); see Milwaukee Brewery Workers’ Pension","paragraph_id":"para_170"},{"text":"Plan v. Jos. Schlitz Brewing Co., 513 U. S. 414, 417 (1995).","paragraph_id":"para_171"},{"text":"Withdrawal liability reflects the employer’s share of the","paragraph_id":"para_172"},{"text":"plan’s unfunded vested benefits (UVBs)—that is, the differ-","paragraph_id":"para_173"},{"text":"ence between the present value of the benefits owed to em-","paragraph_id":"para_174"},{"text":"ployees and the current value of the plan’s assets.","paragraph_id":"para_175"},{"text":"§§1381(b)(1), 1393(c). By requiring employers to pay their","paragraph_id":"para_176"},{"text":"share of the UVBs, ERISA seeks to ensure that plans do not","paragraph_id":"para_177"},{"text":"become insolvent when employers withdraw. Milwaukee","paragraph_id":"para_178"},{"text":"Brewery, 513 U. S., at 416–417.","paragraph_id":"para_179"},{"text":"Section 1391 specifies the methods that plans may use to","paragraph_id":"para_180"},{"text":"calculate withdrawal liability. The common feature of each","paragraph_id":"para_181"},{"text":"method is the requirement that withdrawal liability be cal-","paragraph_id":"para_182"},{"text":"culated based on the plan’s UVBs “as of ” the last day of the","paragraph_id":"para_183"},{"text":"3Cite as: 608 U. S. ____ (2026)","paragraph_id":"para_184"},{"text":"Opinion of the Court","paragraph_id":"para_185"},{"text":"plan year preceding the employer’s withdrawal—the meas-","paragraph_id":"para_186"},{"text":"urement date. See §§1391(b)(2)(E)(i), (c)(2)(C)(i), (3)(A),","paragraph_id":"para_187"},{"text":"(4)(A); Milwaukee Brewery, 513 U. S., at 417–418.","paragraph_id":"para_188"},{"text":"Determining a plan’s UVBs is not a matter of simple","paragraph_id":"para_189"},{"text":"arithmetic. The value of the UVBs depends upon both hard","paragraph_id":"para_190"},{"text":"data about the plan (such as the number of beneficiaries","paragraph_id":"para_191"},{"text":"and the value of the plan’s assets) and a variety of predic-","paragraph_id":"para_192"},{"text":"tions about the future. For example, how many employees","paragraph_id":"para_193"},{"text":"will draw on their benefits and for how long? And what is","paragraph_id":"para_194"},{"text":"the value of those future benefits in today’s dollars?","paragraph_id":"para_195"},{"text":"To make these predictions, a plan’s actuary must select","paragraph_id":"para_196"},{"text":"demographic and economic assumptions about how the","paragraph_id":"para_197"},{"text":"plan’s assets and obligations will change over time. Amer-","paragraph_id":"para_198"},{"text":"ican Academy of Actuaries, Issue Brief: Selection of Actuar-","paragraph_id":"para_199"},{"text":"ial Assumptions for Multiemployer Plans 3 (July 2020). A","paragraph_id":"para_200"},{"text":"key actuarial assumption—the one relevant here—is the","paragraph_id":"para_201"},{"text":"discount rate: the interest rate “used to discount future ben-","paragraph_id":"para_202"},{"text":"efit payments to their present value.” 87 Fed. Reg. 62317","paragraph_id":"para_203"},{"text":"(2022); see Actuarial Standards Board, Actuarial Standard","paragraph_id":"para_204"},{"text":"of Practice No. 27, §3.3 (2023) (ASOP). A higher discount","paragraph_id":"para_205"},{"text":"rate reduces the value of the plan’s UVBs. 87 Fed. Reg.","paragraph_id":"para_206"},{"text":"62317. Lower UVBs, in turn, correspond to a lower with-","paragraph_id":"para_207"},{"text":"drawal liability for employers. Ibid.","paragraph_id":"para_208"},{"text":"Actuaries select the assumptions underlying their UVB","paragraph_id":"para_209"},{"text":"calculations based on relevant “current and historical","paragraph_id":"para_210"},{"text":"data,” ASOP No. 27, §3.5, including growth in the plan’s","paragraph_id":"para_211"},{"text":"earnings, inflation, yields on securities, and other macroe-","paragraph_id":"para_212"},{"text":"conomic conditions, id., §3.7. ERISA imposes few substan-","paragraph_id":"para_213"},{"text":"tive requirements on the selection of these assumptions.","paragraph_id":"para_214"},{"text":"Section 1393, which governs the use of actuarial assump-","paragraph_id":"para_215"},{"text":"tions in calculating withdrawal liability, says only that the","paragraph_id":"para_216"},{"text":"actuary must use “actuarial assumptions and methods","paragraph_id":"para_217"},{"text":"which, in the aggregate, are reasonable (taking into account","paragraph_id":"para_218"},{"text":"the experience of the plan and reasonable expectations) and","paragraph_id":"para_219"},{"text":"4 M & K EMPLOYEE SOLUTIONS, LLC v. TRUSTEES OF","paragraph_id":"para_220"},{"text":"IAM NAT. PENSION FUND","paragraph_id":"para_221"},{"text":"Opinion of the Court","paragraph_id":"para_222"},{"text":"which, in combination, offer the actuary’s best estimate of","paragraph_id":"para_223"},{"text":"anticipated experience under the plan.” §1393(a)(1).1","paragraph_id":"para_224"},{"text":"B","paragraph_id":"para_225"},{"text":"The IAM National Pension Fund (Fund) is an MPP serv-","paragraph_id":"para_226"},{"text":"ing employees who are covered by collective bargaining","paragraph_id":"para_227"},{"text":"agreements with the International Association of Machin-","paragraph_id":"para_228"},{"text":"ists and Aerospace Workers. In November 2017, its actuar-","paragraph_id":"para_229"},{"text":"ial firm, Cheiron, published the annual valuation of the","paragraph_id":"para_230"},{"text":"Fund’s assets and liabilities for the 2016 Plan Year. Using","paragraph_id":"para_231"},{"text":"a discount rate of 7.50%, Cheiron valued the Fund’s UVBs","paragraph_id":"para_232"},{"text":"at close to $500 million. Two months later, on January 24,","paragraph_id":"para_233"},{"text":"2018, Cheiron met with the Fund’s trustees to discuss the","paragraph_id":"para_234"},{"text":"actuarial assumptions it would use to calculate withdrawal","paragraph_id":"para_235"},{"text":"liability for employers who withdrew in 2018. They settled","paragraph_id":"para_236"},{"text":"on a discount rate of 6.50%, 1% lower than the rate previ-","paragraph_id":"para_237"},{"text":"ously used. Cheiron published its actuarial valuation for","paragraph_id":"para_238"},{"text":"Plan Year 2017 on April 17, 2019. Using the 6.50% discount","paragraph_id":"para_239"},{"text":"rate, it valued the Fund’s UVBs at just over $3 billion—six","paragraph_id":"para_240"},{"text":"times the prior year’s figure.","paragraph_id":"para_241"},{"text":"Petitioners are four employers who used to contribute to","paragraph_id":"para_242"},{"text":"the Fund. Each withdrew from the Fund between April and","paragraph_id":"para_243"},{"text":"December 2018. Pursuant to §1391, the Fund assessed","paragraph_id":"para_244"},{"text":"each employer’s withdrawal liability “as of ” December 31,","paragraph_id":"para_245"},{"text":"2017 (the last day of the plan year preceding the year in","paragraph_id":"para_246"},{"text":"which they withdrew). The Fund applied the 6.50% dis-","paragraph_id":"para_247"},{"text":"count rate adopted in January 2018 to calculate their with-","paragraph_id":"para_248"},{"text":"drawal liability. Using the 6.50% discount rate, as com-","paragraph_id":"para_249"},{"text":"pared to the previously adopted 7.50% discount rate,","paragraph_id":"para_250"},{"text":"dramatically increased petitioners’ withdrawal liability;","paragraph_id":"para_251"},{"text":"M&K Employee Solutions, for example, was assessed with-","paragraph_id":"para_252"},{"text":"drawal liability of around $6.2 million, whereas it would","paragraph_id":"para_253"},{"text":"——————","paragraph_id":"para_254"},{"text":"1 In the alternative, the actuary can use “assumptions and methods set","paragraph_id":"para_255"},{"text":"forth in the [Pension Benefit Guaranty Corporation’s] regulations.” 29","paragraph_id":"para_256"},{"text":"U. S. C. §1393(a)(2); see §1301(a)(4). This alternative is not at issue","paragraph_id":"para_257"},{"text":"here.","paragraph_id":"para_258"},{"text":"5Cite as: 608 U. S. ____ (2026)","paragraph_id":"para_259"},{"text":"Opinion of the Court","paragraph_id":"para_260"},{"text":"have owed only around $1.8 million using the prior assump-","paragraph_id":"para_261"},{"text":"tions.","paragraph_id":"para_262"},{"text":"Petitioners initiated separate arbitrations to challenge","paragraph_id":"para_263"},{"text":"their withdrawal-liability assessments. See §1401(a). Each","paragraph_id":"para_264"},{"text":"of the arbitrators determined that the assessment was er-","paragraph_id":"para_265"},{"text":"roneous because the Fund had applied actuarial assump-","paragraph_id":"para_266"},{"text":"tions adopted after December 31, 2017. Doing so, the arbi-","paragraph_id":"para_267"},{"text":"trators reasoned, conflicted with §1391’s requirement that","paragraph_id":"para_268"},{"text":"withdrawal liability be calculated “as of ” the measurement","paragraph_id":"para_269"},{"text":"date. The arbitrators instead required the Fund to use the","paragraph_id":"para_270"},{"text":"actuarial assumptions that were “in effect” on the measure-","paragraph_id":"para_271"},{"text":"ment date—i.e., the 7.50% discount rate. App. 293 (empha-","paragraph_id":"para_272"},{"text":"sis deleted); see also id., at 26–27, 49, 71.","paragraph_id":"para_273"},{"text":"The Fund sought review of the arbitral awards in Federal","paragraph_id":"para_274"},{"text":"District Court. Three of the actions were consolidated,","paragraph_id":"para_275"},{"text":"while the fourth proceeded separately. In both cases, the","paragraph_id":"para_276"},{"text":"District Courts disagreed with the arbitrators, holding that","paragraph_id":"para_277"},{"text":"actuaries could use assumptions adopted after the meas-","paragraph_id":"para_278"},{"text":"urement date to calculate withdrawal liability. 2022 WL","paragraph_id":"para_279"},{"text":"4534998, *11 (D DC, Sept. 28, 2022); Trustees of the IAM","paragraph_id":"para_280"},{"text":"Nat. Pension Fund v. Ohio Magnetics, Inc., 656 F. Supp. 3d","paragraph_id":"para_281"},{"text":"112, 136–137 (DC 2023).","paragraph_id":"para_282"},{"text":"In a consolidated appeal, the Court of Appeals for the","paragraph_id":"para_283"},{"text":"D. C. Circuit affirmed. 92 F. 4th 316, 322 (2024). The court","paragraph_id":"para_284"},{"text":"reasoned that “requir[ing] an actuary to determine what as-","paragraph_id":"para_285"},{"text":"sumptions to use before the close of business on the meas-","paragraph_id":"para_286"},{"text":"urement date” would conflict with Congress’s instruction in","paragraph_id":"para_287"},{"text":"§1393(a)(1) “that an actuary use its ‘best estimate’ of the","paragraph_id":"para_288"},{"text":"plan’s anticipated experience as of the measurement date.”","paragraph_id":"para_289"},{"text":"Id., at 322–323. Accordingly, the court held that actuaries","paragraph_id":"para_290"},{"text":"could adopt assumptions after the measurement date as","paragraph_id":"para_291"},{"text":"long as the assumptions were “based on the body of","paragraph_id":"para_292"},{"text":"knowledge available up to the measurement date.” Id., at","paragraph_id":"para_293"},{"text":"322 (internal quotation marks omitted).","paragraph_id":"para_294"},{"text":"The D. C. Circuit’s decision conflicted with a decision of","paragraph_id":"para_295"},{"text":"the Second Circuit, which held that MPPs must adopt their","paragraph_id":"para_296"},{"text":"6 M & K EMPLOYEE SOLUTIONS, LLC v. TRUSTEES OF","paragraph_id":"para_297"},{"text":"IAM NAT. PENSION FUND","paragraph_id":"para_298"},{"text":"Opinion of the Court","paragraph_id":"para_299"},{"text":"interest rate assumptions for withdrawal-liability purposes","paragraph_id":"para_300"},{"text":"on or before the measurement date. National Retirement","paragraph_id":"para_301"},{"text":"Fund v. Metz Culinary Mgmt., Inc., 946 F. 3d 146, 152","paragraph_id":"para_302"},{"text":"(2020). We granted certiorari to resolve this split over when","paragraph_id":"para_303"},{"text":"actuarial assumptions may be selected for purposes of cal-","paragraph_id":"para_304"},{"text":"culating withdrawal liability. 606 U. S. 930, amended 606","paragraph_id":"para_305"},{"text":"U. S. 958 (2025).2 For the reasons that follow, we now hold","paragraph_id":"para_306"},{"text":"that withdrawal liability can be calculated based on actu-","paragraph_id":"para_307"},{"text":"arial assumptions adopted after the measurement date.","paragraph_id":"para_308"},{"text":"II","paragraph_id":"para_309"},{"text":"Two sections of ERISA govern the calculation of with-","paragraph_id":"para_310"},{"text":"drawal liability: §§1391 and 1393. Neither requires that","paragraph_id":"para_311"},{"text":"actuarial assumptions be selected on or before the measure-","paragraph_id":"para_312"},{"text":"ment date.","paragraph_id":"para_313"},{"text":"A","paragraph_id":"para_314"},{"text":"Section 1391 lays out the various methods that plans can","paragraph_id":"para_315"},{"text":"use to calculate withdrawal liability. It does not mention","paragraph_id":"para_316"},{"text":"actuarial assumptions at all. Nevertheless, petitioners ask","paragraph_id":"para_317"},{"text":"us to identify a deadline for the selection of assumptions","paragraph_id":"para_318"},{"text":"from §1391’s directive that withdrawal liability be calcu-","paragraph_id":"para_319"},{"text":"lated based on the plan’s UVBs “as of ” the measurement","paragraph_id":"para_320"},{"text":"date. See, e.g., §1391(b)(2)(E)(i). But the “as of ” language","paragraph_id":"para_321"},{"text":"sets no such deadline.","paragraph_id":"para_322"},{"text":"Dictionaries define “as of ” to mean “at the date men-","paragraph_id":"para_323"},{"text":"tioned.” Oxford American Dictionary 34 (1980); see also","paragraph_id":"para_324"},{"text":"Webster’s Third New International Dictionary 129 (1976)","paragraph_id":"para_325"},{"text":"(“at or on (a specific time or date)”). In context, the term is","paragraph_id":"para_326"},{"text":"understood “to assign an event to one time and the recogni-","paragraph_id":"para_327"},{"text":"tion of it to another.” W. Follett, Modern American Usage","paragraph_id":"para_328"},{"text":"41 (rev. ed. 1998). Thus, §1391’s use of “as of ” means two","paragraph_id":"para_329"},{"text":"things. First, the hard data about the plan that feeds the","paragraph_id":"para_330"},{"text":"——————","paragraph_id":"para_331"},{"text":"2 The parties also disputed below whether actuarial assumptions must","paragraph_id":"para_332"},{"text":"be based on only the information available as of the measurement date.","paragraph_id":"para_333"},{"text":"We leave that question for another day.","paragraph_id":"para_334"},{"text":"7Cite as: 608 U. S. ____ (2026)","paragraph_id":"para_335"},{"text":"Opinion of the Court","paragraph_id":"para_336"},{"text":"UVB calculation must be fixed on the measurement date.","paragraph_id":"para_337"},{"text":"Second, and as all agree, the actual UVB calculation can be","paragraph_id":"para_338"},{"text":"performed after the measurement date. For purposes of","paragraph_id":"para_339"},{"text":"this case, then, the key question is whether actuarial as-","paragraph_id":"para_340"},{"text":"sumptions are akin to the facts about the plan that must be","paragraph_id":"para_341"},{"text":"fixed on the measurement date, or whether they are a part","paragraph_id":"para_342"},{"text":"of the UVB calculation itself and can therefore be selected","paragraph_id":"para_343"},{"text":"after the measurement date.","paragraph_id":"para_344"},{"text":"Petitioners argue that actuarial assumptions are factual","paragraph_id":"para_345"},{"text":"inputs into the UVB calculation, much like hard data such","paragraph_id":"para_346"},{"text":"as the number of plan beneficiaries. On this view, to comply","paragraph_id":"para_347"},{"text":"with §1391, the actuarial assumptions must be “frozen” on","paragraph_id":"para_348"},{"text":"the measurement date. Brief for Petitioners 23. In other","paragraph_id":"para_349"},{"text":"words, they say, the actuary must use the assumptions that","paragraph_id":"para_350"},{"text":"are “in effect” on the measurement date—i.e., the assump-","paragraph_id":"para_351"},{"text":"tions most recently adopted before the measurement date—","paragraph_id":"para_352"},{"text":"to value the UVBs. Brief for Petitioners 37.","paragraph_id":"para_353"},{"text":"But petitioners’ argument is based on a flawed under-","paragraph_id":"para_354"},{"text":"standing of actuarial assumptions. These assumptions are","paragraph_id":"para_355"},{"text":"not factual inputs. Instead, they are predictive judgments","paragraph_id":"para_356"},{"text":"about a plan’s anticipated future performance—tools actu-","paragraph_id":"para_357"},{"text":"aries use to calculate the plan’s UVBs. The distinction be-","paragraph_id":"para_358"},{"text":"tween tool and fact is clear from the text of ERISA: Section","paragraph_id":"para_359"},{"text":"1393 groups actuarial assumptions together with “meth-","paragraph_id":"para_360"},{"text":"ods” in prescribing how withdrawal liability must be calcu-","paragraph_id":"para_361"},{"text":"lated. See §1393(a)(1). The relevant similarity between as-","paragraph_id":"para_362"},{"text":"sumptions and methods is that both are tools used to make","paragraph_id":"para_363"},{"text":"actuarial valuations. See, e.g., §1393(a) (referring to actu-","paragraph_id":"para_364"},{"text":"arial assumptions as something “used” to determine UVBs);","paragraph_id":"para_365"},{"text":"§1401(a)(3)(B)(i) (same).","paragraph_id":"para_366"},{"text":"The Actuarial Standards of Practice likewise support our","paragraph_id":"para_367"},{"text":"conclusion that actuarial assumptions are not observable","paragraph_id":"para_368"},{"text":"facts about the plan that are “in effect” on a particular","paragraph_id":"para_369"},{"text":"8 M & K EMPLOYEE SOLUTIONS, LLC v. TRUSTEES OF","paragraph_id":"para_370"},{"text":"IAM NAT. PENSION FUND","paragraph_id":"para_371"},{"text":"Opinion of the Court","paragraph_id":"para_372"},{"text":"date.3 These professional guidelines instruct actuaries to","paragraph_id":"para_373"},{"text":"select assumptions for the purpose of making a particular","paragraph_id":"para_374"},{"text":"calculation or measurement. See ASOP No. 27, §3.3 (“The","paragraph_id":"para_375"},{"text":"actuary should identify the types of assumptions to use for","paragraph_id":"para_376"},{"text":"a specific measurement,” taking into account, among other","paragraph_id":"para_377"},{"text":"things, “the purpose of the measurement”); id., §3.8 (“The","paragraph_id":"para_378"},{"text":"actuary should take into account the purpose of the meas-","paragraph_id":"para_379"},{"text":"urement as a primary factor in selecting a discount rate”).","paragraph_id":"para_380"},{"text":"In other words, actuaries make assumptions when the need","paragraph_id":"para_381"},{"text":"for an actuarial valuation arises.","paragraph_id":"para_382"},{"text":"In this case, for example, the Fund’s actuary adopted as-","paragraph_id":"para_383"},{"text":"sumptions for purposes of its 2016 Plan Year annual valu-","paragraph_id":"para_384"},{"text":"ation. The Fund then adopted new actuarial assumptions","paragraph_id":"para_385"},{"text":"for purposes of calculating withdrawal liability for employ-","paragraph_id":"para_386"},{"text":"ers who withdrew in 2018, and later for its 2017 Plan Year","paragraph_id":"para_387"},{"text":"annual valuation. As this case illustrates, actuarial as-","paragraph_id":"para_388"},{"text":"sumptions are adopted for the purpose of a particular cal-","paragraph_id":"para_389"},{"text":"culation or measurement; they are not generally “in effect”","paragraph_id":"para_390"},{"text":"in the way that petitioners urge.","paragraph_id":"para_391"},{"text":"With this understanding of actuarial assumptions, peti-","paragraph_id":"para_392"},{"text":"tioners’ proposed interpretation of §1391 falls apart. Be-","paragraph_id":"para_393"},{"text":"cause actuarial assumptions are tools used to calculate","paragraph_id":"para_394"},{"text":"UVBs rather than hard data about the plan, they cannot be","paragraph_id":"para_395"},{"text":"“frozen” on the measurement date. Section 1391’s “as of ”","paragraph_id":"para_396"},{"text":"requirement sets the reference point for the factual inputs","paragraph_id":"para_397"},{"text":"into the UVB calculation. It has no bearing on when actu-","paragraph_id":"para_398"},{"text":"aries must select the tools, including assumptions, they use","paragraph_id":"para_399"},{"text":"to calculate a plan’s UVBs.","paragraph_id":"para_400"},{"text":"——————","paragraph_id":"para_401"},{"text":"3 Consulting the Actuarial Standards of Practice is appropriate here","paragraph_id":"para_402"},{"text":"because this is a statute “addressed to specialists,” so it “must be read by","paragraph_id":"para_403"},{"text":"judges with the minds of the specialists.” Becerra v. Empire Health","paragraph_id":"para_404"},{"text":"Foundation, for Valley Hospital Medical Center, 597 U. S. 424, 434 (2022)","paragraph_id":"para_405"},{"text":"(internal quotation marks omitted).","paragraph_id":"para_406"},{"text":"9Cite as: 608 U. S. ____ (2026)","paragraph_id":"para_407"},{"text":"Opinion of the Court","paragraph_id":"para_408"},{"text":"B","paragraph_id":"para_409"},{"text":"Section 1393, the section of ERISA that governs the use","paragraph_id":"para_410"},{"text":"of actuarial assumptions for assessing withdrawal liability,","paragraph_id":"para_411"},{"text":"confirms that the measurement date is not a deadline by","paragraph_id":"para_412"},{"text":"which actuaries must select their assumptions. Indeed,","paragraph_id":"para_413"},{"text":"§1393 provides no deadline at all. The statute merely says","paragraph_id":"para_414"},{"text":"that the actuary’s assumptions must be “reasonable,” must","paragraph_id":"para_415"},{"text":"“tak[e] into account the experience of the plan and reason-","paragraph_id":"para_416"},{"text":"able expectations,” and must “offer the actuary’s best esti-","paragraph_id":"para_417"},{"text":"mate of anticipated experience under the plan.”","paragraph_id":"para_418"},{"text":"§1393(a)(1). We generally do not read limitations into stat-","paragraph_id":"para_419"},{"text":"utes that do not appear in their text, Romag Fasteners, Inc.","paragraph_id":"para_420"},{"text":"v. Fossil Group, Inc., 590 U. S. 212, 215 (2020), and we dis-","paragraph_id":"para_421"},{"text":"cern no basis for doing so here.","paragraph_id":"para_422"},{"text":"The omission of any deadline in §1393 is significant given","paragraph_id":"para_423"},{"text":"Congress’s inclusion of a similar deadline in a different sec-","paragraph_id":"para_424"},{"text":"tion of the statute. Specifically: The amortization period for","paragraph_id":"para_425"},{"text":"an employer’s withdrawal-liability payments must be de-","paragraph_id":"para_426"},{"text":"termined based on “the assumptions used for the most re-","paragraph_id":"para_427"},{"text":"cent actuarial valuation for the plan.” §1399(c)(1)(A)(ii).","paragraph_id":"para_428"},{"text":"But Congress imposed no similar limit for the actuarial as-","paragraph_id":"para_429"},{"text":"sumptions used to calculate withdrawal liability; we pre-","paragraph_id":"para_430"},{"text":"sume this omission is intentional. See Russello v. United","paragraph_id":"para_431"},{"text":"States, 464 U. S. 16, 23 (1983) (“[W]here Congress includes","paragraph_id":"para_432"},{"text":"particular language in one section of a statute but omits it","paragraph_id":"para_433"},{"text":"in another section of the same Act, it is generally presumed","paragraph_id":"para_434"},{"text":"that Congress acts intentionally and purposely in the dis-","paragraph_id":"para_435"},{"text":"parate inclusion or exclusion” (internal quotation marks","paragraph_id":"para_436"},{"text":"omitted)).","paragraph_id":"para_437"},{"text":"Moreover, §1393’s instruction that actuarial assumptions","paragraph_id":"para_438"},{"text":"reflect the actuary’s “best estimate of anticipated experi-","paragraph_id":"para_439"},{"text":"ence under the plan,” §1393(a)(1), supports the conclusion","paragraph_id":"para_440"},{"text":"that actuaries can select their assumptions after the meas-","paragraph_id":"para_441"},{"text":"urement date. Recall that actuaries choose assumptions","paragraph_id":"para_442"},{"text":"based on the plan’s past performance, changes in the mar-","paragraph_id":"para_443"},{"text":"ket, and other relevant information. ASOP No. 27, §3.5.","paragraph_id":"para_444"},{"text":"10 M & K EMPLOYEE SOLUTIONS, LLC v. TRUSTEES OF","paragraph_id":"para_445"},{"text":"IAM NAT. PENSION FUND","paragraph_id":"para_446"},{"text":"Opinion of the Court","paragraph_id":"para_447"},{"text":"Thus, the assumptions should “reflect the actuary’s","paragraph_id":"para_448"},{"text":"knowledge as of the measurement date.” id., §3.4.6. But","paragraph_id":"para_449"},{"text":"the relevant information about the plan’s performance or","paragraph_id":"para_450"},{"text":"macroeconomic conditions, as it stood on the measurement","paragraph_id":"para_451"},{"text":"date, may not become available until after the measure-","paragraph_id":"para_452"},{"text":"ment date. See American Academy of Actuaries, Issue","paragraph_id":"para_453"},{"text":"Brief: Selection of Actuarial Assumptions for Multiem-","paragraph_id":"para_454"},{"text":"ployer Plans 4. Requiring actuaries to use assumptions se-","paragraph_id":"para_455"},{"text":"lected before the measurement date could therefore prevent","paragraph_id":"para_456"},{"text":"them from relying on the most up-to-date data when select-","paragraph_id":"para_457"},{"text":"ing their assumptions. This, in turn, could mean that their","paragraph_id":"para_458"},{"text":"assumptions do not reflect their “best estimate.”","paragraph_id":"para_459"},{"text":"§1393(a)(1).","paragraph_id":"para_460"},{"text":"More fundamentally, requiring actuaries to use assump-","paragraph_id":"para_461"},{"text":"tions based on stale data would result in an incoherent stat-","paragraph_id":"para_462"},{"text":"utory scheme. Under petitioners’ view, actuaries must","paragraph_id":"para_463"},{"text":"value a plan’s UVBs based on hard data as it stood on the","paragraph_id":"para_464"},{"text":"measurement date while at the same time applying as-","paragraph_id":"para_465"},{"text":"sumptions selected based on an older set of facts. The stat-","paragraph_id":"para_466"},{"text":"ute does not mandate this mismatch. Instead, actuaries","paragraph_id":"para_467"},{"text":"may select their assumptions after the measurement date","paragraph_id":"para_468"},{"text":"in order to value the UVBs as of the measurement date.","paragraph_id":"para_469"},{"text":"III","paragraph_id":"para_470"},{"text":"Unable to identify a deadline for adopting actuarial as-","paragraph_id":"para_471"},{"text":"sumptions in the text of ERISA, petitioners turn to two","paragraph_id":"para_472"},{"text":"other arguments—one about statutory context and the","paragraph_id":"para_473"},{"text":"other related to policy concerns. Neither has merit.","paragraph_id":"para_474"},{"text":"First, petitioners contend that the statute contains a","paragraph_id":"para_475"},{"text":"broad antiretroactivity principle. They point to a different","paragraph_id":"para_476"},{"text":"section of ERISA, §1394, for support. This section prohibits","paragraph_id":"para_477"},{"text":"plans from applying any new “plan rule or amendment” to","paragraph_id":"para_478"},{"text":"an employer’s withdrawal liability if the rule or amendment","paragraph_id":"para_479"},{"text":"is adopted after the employer withdraws. §1394(a).","paragraph_id":"para_480"},{"text":"But this section hurts rather than helps petitioners. As","paragraph_id":"para_481"},{"text":"they acknowledge, actuarial assumptions are not plan rules","paragraph_id":"para_482"},{"text":"11Cite as: 608 U. S. ____ (2026)","paragraph_id":"para_483"},{"text":"Opinion of the Court","paragraph_id":"para_484"},{"text":"or amendments. Accordingly, the retroactivity limits in","paragraph_id":"para_485"},{"text":"§1394 do not apply to actuarial assumptions. Congress","paragraph_id":"para_486"},{"text":"chose not to enact a similar antiretroactivity rule in §1393,","paragraph_id":"para_487"},{"text":"which strongly suggests that actuarial assumptions are not","paragraph_id":"para_488"},{"text":"subject to any such limitation. See Russello, 464 U. S., at","paragraph_id":"para_489"},{"text":"23. Inferring an antiretroactivity rule for the selection of","paragraph_id":"para_490"},{"text":"actuarial assumptions would override Congress’s choice.","paragraph_id":"para_491"},{"text":"So petitioners fall back on a policy argument. They con-","paragraph_id":"para_492"},{"text":"tend that allowing plans to adopt actuarial assumptions af-","paragraph_id":"para_493"},{"text":"ter the measurement date will open the door to manipula-","paragraph_id":"para_494"},{"text":"tion. Plans and their actuaries, petitioners worry, will","paragraph_id":"para_495"},{"text":"retroactively select assumptions in order to increase with-","paragraph_id":"para_496"},{"text":"drawing employers’ liability. But their proposed rule—that","paragraph_id":"para_497"},{"text":"withdrawal liability must be based on assumptions adopted","paragraph_id":"para_498"},{"text":"before the measurement date—does nothing to address","paragraph_id":"para_499"},{"text":"these concerns. Plans and actuaries could still select as-","paragraph_id":"para_500"},{"text":"sumptions with an eye towards inflating withdrawal liabil-","paragraph_id":"para_501"},{"text":"ity before the measurement date given the significant dis-","paragraph_id":"para_502"},{"text":"cretion they enjoy in selecting assumptions.","paragraph_id":"para_503"},{"text":"In any event, “policy concerns cannot trump the best in-","paragraph_id":"para_504"},{"text":"terpretation of the statutory text.” Patel v. Garland, 596","paragraph_id":"para_505"},{"text":"U. S. 328, 346 (2022). Congress chose which limits to im-","paragraph_id":"para_506"},{"text":"pose on the selection of actuarial assumptions. The statute","paragraph_id":"para_507"},{"text":"requires that actuarial assumptions be “reasonable” and re-","paragraph_id":"para_508"},{"text":"flect actuaries’ “best estimate.” §1393(a)(1). And the stat-","paragraph_id":"para_509"},{"text":"ute permits employers to challenge actuarial assumptions","paragraph_id":"para_510"},{"text":"in arbitration, including on the ground that they were “un-","paragraph_id":"para_511"},{"text":"reasonable.” §1401(a)(3)(B)(i). Indeed, many of the worst-","paragraph_id":"para_512"},{"text":"case scenarios petitioners posit—for example, that actuar-","paragraph_id":"para_513"},{"text":"ies will adopt intentionally low discount rates for with-","paragraph_id":"para_514"},{"text":"drawal liability but high discount rates for other pur-","paragraph_id":"para_515"},{"text":"poses—are subject to challenge in arbitration. It is not the","paragraph_id":"para_516"},{"text":"role of the Court to supplant Congress’s choices, as reflected","paragraph_id":"para_517"},{"text":"in the statutory text, with our own.","paragraph_id":"para_518"},{"text":"12 M & K EMPLOYEE SOLUTIONS, LLC v. TRUSTEES OF","paragraph_id":"para_519"},{"text":"IAM NAT. PENSION FUND","paragraph_id":"para_520"},{"text":"Opinion of the Court","paragraph_id":"para_521"},{"text":"* * *","paragraph_id":"para_522"},{"text":"ERISA does not require pension plans to assess with-","paragraph_id":"para_523"},{"text":"drawal liability based on actuarial assumptions adopted be-","paragraph_id":"para_524"},{"text":"fore the measurement date. We therefore affirm the judg-","paragraph_id":"para_525"},{"text":"ment of the D. C. 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