Business Registration Number: What It Is and How to Find Yours
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Short answer: in the U.S., "business registration number" isn't a single number. Depending on who's asking, it usually means one of four things: your federal EIN, your state entity (file) number from the Secretary of State, your state tax or sales tax ID, or your local business license number. A bank, a vendor form and a government portal may each want a different one. This guide explains each, who has one, and exactly where to find it.
The four numbers people mean
| Number | Issued by | Who has one | Typically used for |
|---|---|---|---|
| EIN (Employer Identification Number) | IRS | Corporations, multi-member LLCs, any business with employees, and optionally sole proprietors and single-member LLCs | Federal tax returns, payroll, W-9s, bank accounts |
| State entity / file number | Secretary of State (or equivalent) | Registered entities: LLCs, corporations, LPs, LLPs | Annual reports, certificates of good standing, state filings |
| State tax ID / sales tax permit number | State revenue or tax department | Businesses that collect sales tax or withhold state payroll tax | Sales tax returns, resale certificates |
| Local business license number | City or county | Businesses required to hold a local license (rules vary) | Local compliance, sometimes vendor onboarding |
Sole proprietors: you may not have a "registration number" at all
A sole proprietorship isn't registered with the state as an entity, so it has no Secretary of State file number. If you operate under a name other than your own, your DBA or assumed name filing will usually have a file or certificate number from the county or state that took the filing. That's often what a form means by "registration number" for a sole proprietor. If a form insists on a number you don't have, look for an option such as "sole proprietor / not registered," or use your EIN or DBA file number as the form instructs.
New to naming and DBAs? See our guide to sole proprietorship name rules.
How to find your EIN
- Check your IRS confirmation notice. When an EIN is issued, the IRS sends a confirmation notice (commonly the CP 575). If you applied online, you could download it at the end of the application.
- Look at past filings. Prior federal tax returns, payroll filings, and 1099s you issued show the EIN.
- Ask your bank or payroll provider. Your business bank account and payroll service have it on file.
- Call the IRS. An authorized person (for example, the owner or a corporate officer) can call the IRS Business & Specialty Tax Line and request the number. The IRS can also send a verification letter (147C).
The IRS Business & Specialty Tax Line is 800-829-4933 (Monday to Friday, 7 a.m. to 7 p.m. local time). The assistor will verify your identity and confirm you're authorized, for example as the sole proprietor, a partner or a corporate officer.
How to find your state entity (file) number
- Go to your state Secretary of State's business entity search. Most states offer it free online.
- Search by your exact legal entity name, including "LLC" or "Inc."
- The record shows the entity or file number, status (active, inactive, dissolved), formation date, and registered agent.
The same number appears on your articles of organization or incorporation and on annual report filings. If your business is registered in more than one state (for example, formed in one and "foreign qualified" in another), each state issues its own number.
How to find your state tax or sales tax ID
It's printed on your sales tax permit or seller's certificate and on any state tax notice you've received. You can also log in to your state's online tax account. If you sell taxable goods or services from home and never registered, check your state revenue department's site. Many states require a permit before your first taxable sale.
How to find your local business license number
It's on the license certificate and renewal notices from your city or county. If you run the business from home, the city may also have issued a home occupation permit with its own number.
Other IDs you might be asked for
- UEI (Unique Entity ID): required to register in SAM.gov for federal contracts and grants. It replaced the DUNS number for federal purposes in 2022.
- D-U-N-S Number: a Dun & Bradstreet identifier some suppliers and lenders still request for business credit files.
- NAICS code: not an ID but a six-digit industry code, often requested on the same forms.
Frequently asked questions
Is a business registration number the same as an EIN?
Not always. An EIN is a federal tax ID. "Business registration number" more often means the state entity number. If a form is unclear, check whether it's a tax form (usually EIN) or a state or vendor form (often state file number).
Can I look up another company's registration number?
State entity numbers are public and searchable on Secretary of State sites. EINs are not published in a public IRS directory, although they can appear on documents such as nonprofit filings.
Does my business need a registration number to operate?
LLCs and corporations must be registered with the state, so they always have one. Sole proprietors don't register as entities but may still need a DBA filing, a sales tax permit, and local licenses depending on what and where they sell.
This guide is general information, not legal or tax advice. Requirements vary by state and locality.
Questions? Ask the community or browse more home business guides.