USA company registration number: Essential guide for founders

Key differences between Employer Identification Number and State Entity Number

The Employer Identification Number and State Entity Number are two different identifiers for the same business. However, these two numbers work separately for separate purposes, like:

The EIN remains constant regardless of where you expand in the US. The state registration number, however, varies from state to state. So, you need a new state registration number if you decide to register your business into another US state.

If you register as a foreign entity in another state, you will receive a different state entity number there. The EIN is used for federal tax administration, while state filling authorities maintain the state entity numbers.

The Employer Identification Number (EIN)

Your EIN is the closest thing the USA has to a universal business identifier. It's a 9-digit number assigned by the Internal Revenue Service (IRS), formatted as XX-XXXXXXX.

The EIN tracks federal taxes and payroll obligations. You'll need it to open a business bank account, apply for business loans, hire employees, and file federal tax returns. Most financial institutions and government agencies will ask for it.

How to obtain an EIN

To obtain an EIN, your company needs to be eligible for a federal tax ID number. The IRS issues an Employer Identification Number based on the information provided in Form SS-4. The IRS offers three methods to get an EIN, each with different processing times:

• Online application: Eligible applicants can complete the IRS online application in one session and receive the EIN after successful approval.
• Fax application: Download Form SS-4, fill it out, and fax it to the IRS. For fax application, you may receive your EIN number within a week. Keep this document accessible, you'll reference it constantly.
• Mail application: You can also send your completed Form SS-4 to the IRS via postal mail. However, this method takes the longest, about 4-5 weeks, to receive your EIN.

If the assignment notice is unavailable, check previously filed federal tax returns, payroll records and prior business-account or credit applications. Make sure that your company information in Form SS-4 is accurate to avoid any discrepancies later. If you've already applied, you should have received a confirmation letter (Form CP 575) from the IRS where you can find your EIN number. Keep this document accessible—you'll reference it constantly.

Is the business registration number the same as EIN?

No. An EIN is a federal tax identifier issued by the IRS, while a state business registration number is issued by the state where the company is formed or registered. People may use “business registration number” informally for either identifier, but the two numbers are not interchangeable.

A Delaware LLC may have one federal EIN and a separate Delaware file number. If it later registers in another state, that state may issue another entity number while the federal EIN generally remains the same.

State registration numbers & company IDs

When you register your startup in any USA state, the state government automatically issues an entity ID, or the State Registration Number. The number identifies the business in the state’s filing system. The registry may separately show whether the entity is active, inactive, dissolved or in good standing. Every U.S. state maintains its own business registry. When you file your Articles of Incorporation (for corporations) or Articles of Organization (for LLCs), the state assigns you a unique identifier.

This US Business Registration Number (BRN) goes by different names depending on where you're registered. Some states call it a Company ID (CID), others use terms like Entity Number, Charter Number, or File Number. For example, a business incorporated in Texas will have a Texas File Number, while one in Washington will have a Washington UBI (Unified Business Identifier). The format and length vary by state. Some are purely numeric, others include letters. There's no standardization across the country.

Some states require an additional state entity ID for payroll taxes, sales tax, or other state-specific obligations. Check your state's Department of Revenue or Taxation website to confirm what's required.

Here’s how to find your business registration number by state:

Processing times vary by state, filing method and service level. Check the relevant state filing authority for current estimates.The number identifies the business in that jurisdiction’s filing system. Check the accompanying record to determine its current status. You'll need it for state tax filings, annual reports, and any legal documents filed within that state. If you're expanding to multiple states, you'll have a different registration number in each one.

How to find a USA company registration number

To find a US company registration number, whether you are looking for the federal EIN or the state-issued state registration number, there are three steps to follow:

Step 1: Identify which business identifier is being requested, such as an EIN, state entity number, tax account number or license ID.

Step 2: Check your documents. If you are searching for your own US company register number, then your business documents will have it.

Step 3: Use the online databases. This can be helpful if you’re searching for someone else’s US company registration number.

Here's where to find business registration number for your or someone else’s company:

Searching for your own business

Both your EIN and State Registration Numbers appear on different documents that may be available to you as soon as your business is registered with the federal and state agencies.

• Check your IRS EIN confirmation letter (Form CP 575): If you apply online, you will receive the confirmation letter immediately. If you apply by fax or mail, the IRS mails it to your business address.
• Review your business tax returns: Your EIN appears on every federal tax return you've filed, including Form 1120 (C-corporations), Form 1120-S (S-corporations), or Form 1065 (partnership firms).
• Look at your original Articles of Incorporation or Organization: When you register your business with the state, you receive a filed copy of your formation documents. The state business registration number appears on this document, usually in the top corner or footer.
• Check annual report confirmations: If you've filed annual reports with your state, the confirmation emails or letters include your state registration number.

Searching for another business

Since you are looking for another business’s registered company number in the USA, the process to find it differs. The USA has several online government databases for such information.

• Public companies: Use the SEC EDGAR database and search by company name to find the CIK and access all public filings. This database includes detailed financial information, ownership structures, and corporate governance documents.
• Private companies: Navigate to the Secretary of State website for the state where the company is registered. Most states offer a free business entity search tool. You'll need the exact legal name of the business or the name of a registered agent. The search results typically display the company's registration number, formation date, status (active or dissolved), and registered agent information.
• Non-profits: Use the IRS Tax-Exempt Organization Search tool to verify non-profit status and find the EIN. This database includes all organizations recognized as tax-exempt under Section 501(c) of the Internal Revenue Code.
• State-wise databases: If you know the state a business is registered in, you can use state-specific business registration number lookup websites.
• Third-party databases: Tools like OpenCorporates aggregate business registration data from 50+ jurisdictions worldwide, including all U.S. states. These platforms offer a simple search interface, making it easier to find companies when you're unsure which state they're registered in. Third-party databases can help identify a possible jurisdiction, but confirm the entity details in the relevant official state registry.

Here’s what you can find in an official state registry:

• Exact legal name
• State of formation
• Entity or file number
• Formation date
• Current status
• Registered agent
• Foreign registrations
• Whether the record belongs to the intended business

If a company operates in multiple states, it will have a "home state" where it's incorporated. Alongside, it may also have foreign qualification numbers in other states where it operates. You may need to search multiple Secretary of State databases to get the complete picture.

Specialized identifiers and when you need them

For different industries and business structures, you may need additional identifiers beyond the EIN and state registration number.

Why business identifiers are requested

Government agencies, financial providers and business partners may use these identifiers to match the company to official records. The identifier requested depends on the task and authority.

Legitimacy and Know Your Business (KYB) verification

When you're applying for a business bank account, setting up a payment processor, or partnering with another company, they'll verify your business using these identifiers. Financial institutions use them to perform compliance checks.

Financial capability

An EIN is mandatory to open a business bank account in the USA. It is necessary when you want to hire employees. If you are applying for a business credit card, you commonly require an EIN. You may require your state registration number for any legal contracts, real estate transactions, or state-level licenses.

Compliance and reporting

Tax authorities, regulators, and licensing boards use these numbers to track your filings and ensure compliance. If you change your business address, legal structure, or ownership, you need to update your records with both the IRS, state filing authority, tax agency or licensing body. The filing required depends on the type of change. Having this information ensures that you address tax notices in a timely manner, keep your business status active, and uphold good standing.

Scaling across borders

International banks, payment processors, and regulatory authorities will request your US company registration number details to verify your US  business entity. Having these numbers readily available simplifies cross-border transactions and banking relationships.

Final Thoughts

The US gives different company registration numbers for separate purposes. A combination of a federal EIN and a state registration number contributes to creating a complete identity of your business. Your EIN connects your federal obligations, while state registration numbers show compliance with local laws. Keep both numbers easily accessible along with your formation documents, EIN confirmation letter, and any licenses or permits.

When you scale your business, these documents become necessary for every bank application, vendor agreement, tax filing, and compliance requirement. Your company registration numbers are creating a strong base for your company’s market reputation.

Disclosure: AFT US LLC, d/b/a Aspire, is a financial technology company, not a bank. The Deposit Account and banking services are provided by Column N.A., Member FDIC. FDIC deposit insurance covers the failure of an insured depository institution. Deposits in the Deposit Account are FDIC-insured through Column N.A., Member FDIC and Column's Sweep Program Network Banks. Certain conditions must be satisfied for pass-through FDIC insurance to apply‍