A business registration number is an identifier issued when a government agency registers a company. In the United States, the phrase can refer to a state entity number, charter number, file number, tax account number, or local license number. It is not automatically the same as an Employer Identification Number (EIN).
Common business numbers in the United States
| Identifier | Issued by | Main purpose |
|---|---|---|
| State entity or file number | Secretary of State or similar office | Tracks the legal entity and state filings |
| EIN | Internal Revenue Service | Federal tax administration and many banking/payroll tasks |
| State tax account number | State revenue or labor agency | Sales tax, withholding, unemployment, or other state taxes |
| Local license number | City or county | Local permission to conduct regulated business |
| Unique Entity ID | SAM.gov | Identifies entities doing business with the U.S. government |
Business registration number vs. EIN
A state registration number identifies the entity in a state registry. An EIN is a federal taxpayer identifier issued by the IRS. A company may have both, plus several state and local account numbers.
Do not enter a state file number when a form asks for an EIN, and do not publish an EIN as though it were a public state registration number. If you are still choosing a legal form, review LLC vs. Inc. before registering.
Where to find your registration number
- Check approved articles of organization or incorporation.
- Search the official Secretary of State business database.
- Review annual-report notices and certificates of status.
- Check state tax registration letters.
- Review the business license issued by the city or county.
- Contact the issuing agency if the number is still unclear.
Search only official government databases when possible. Third-party sites may display outdated status, charge unnecessary fees, or confuse entities with similar names.
How to look up another company
Start with the state where the entity was formed. Use the official search and try the exact legal name first. If nothing appears:
- remove punctuation and suffixes such as LLC or Inc.;
- search a distinctive part of the name;
- check prior names or mergers;
- confirm whether it is a foreign entity registered from another state; and
- review status, registered agent, formation date, and filing history.
A public entity number does not prove that a business is licensed for every activity, financially healthy, or authorized to solicit investments.
How to obtain the right numbers
- Choose the business structure and formation state.
- File the formation document with the state.
- Receive the state entity number.
- Apply directly to the IRS for an EIN when required.
- Register for state tax accounts based on employees, sales, and activities.
- Obtain required industry and local licenses.
- Apply for a Unique Entity ID in SAM.gov if pursuing federal awards or contracts.
Protect identifiers from misuse
Many state file numbers are public. EINs and payroll credentials should be handled more carefully. Store notices securely, verify requests before sharing documents, and restrict access to government and bank portals. If credentials appear in an unauthorized disclosure, follow the controls in our dark web threat response guide.
Frequently asked questions
Does a sole proprietor have a business registration number?
Possibly. A sole proprietor may have an EIN, assumed-name registration, state tax account, or local business license even without forming a separate legal entity.
Can one business have multiple registration numbers?
Yes. Each state, tax agency, licensing authority, and government program may issue its own identifier.
What if a bank asks for a “business number”?
Ask which identifier it needs. Banks commonly request an EIN, state formation number, or both.
Sources reviewed: U.S. Small Business Administration and IRS EIN guidance. Last reviewed August 15, 2026.
Requirements vary by jurisdiction. This article is not legal or tax advice.