Do I have to register my company in another US state?
Yes, where the activity in that state amounts to doing business there. Registration, tax nexus and sales tax nexus are three separate thresholds, tested state by state, and meeting one does not decide the others.
The answer differs between the federal level and the states, see the rows below.
The answer by level
State level
An entity is governed by the law of the state where it was formed, and that state alone decides its internal affairs.
8 Del. C. Chapter 1Threshold
A company doing business in another state registers there as a foreign entity, appoints a registered agent and files the required certificate before it may bring suit in that state's courts.
8 Del. C. § 371, foreign corporations doing business in DelawareTax treatment
Tax registration follows its own threshold: California treats an entity as doing business when it is organised or commercially domiciled there, or when sales, property or payroll exceed the annual amounts set in the statute.
Cal. Rev. & Tax. Code § 23101, doing business in California
Source lines
- The formation state governs the internal affairs of the entity regardless of where it operates.
- A foreign qualification statute conditions access to the state's courts on registration and a registered agent.
- State tax law sets its own doing business threshold based on organisation, commercial domicile, sales, property or payroll.
What it means for the company
An employee, an office, inventory or a repeated on site service in a state is what usually triggers the duty, not the address on the invoice.
| Level | Requirement | Source |
|---|---|---|
| State level | An entity is governed by the law of the state where it was formed, and that state alone decides its internal affairs. | 8 Del. C. Chapter 1 |
| Threshold | A company doing business in another state registers there as a foreign entity, appoints a registered agent and files the required certificate before it may bring suit in that state's courts. | 8 Del. C. § 371, foreign corporations doing business in Delaware |
| Tax treatment | Tax registration follows its own threshold: California treats an entity as doing business when it is organised or commercially domiciled there, or when sales, property or payroll exceed the annual amounts set in the statute. | Cal. Rev. & Tax. Code § 23101, doing business in California |
What it means for the individual
An unregistered company may be barred from suing in that state until it registers and pays the accumulated fees and penalties.
Source lines
- Delaware General Corporation Law8 Del. C. Chapter 1 · read 2026-08-25 · proof b44bbe65a3be9464
- Delaware Code Online8 Del. C. § 371, foreign corporations doing business in Delaware · read 2026-08-25 · proof b44bbe65a3be9464Official source
- California Franchise Tax BoardCal. Rev. & Tax. Code § 23101, doing business in California · read 2026-08-25 · proof b44bbe65a3be9464Official source
Next step
List every state with an employee, a place of business or physical property, and test registration, income tax and sales tax separately for each.
This page reports what the sources say, with the identifier and address of the publisher. It is not legal advice and does not decide an individual matter.
Next step
Three ways to put the register to work in your own practice.
Start with your task
Litigation
Find support in a judgment
Search guiding decisions, see what became final and follow changes in the law.
In-house, deals
Map the rules in a transaction
Move from theme to act and on to the article that carries the duty.
Compliance
Assess the risk in a process
Risk scoring per legal area, with the sources behind every score.