Company Registration Number Check: Same Legal Entity on Every Supplier Document

This article is provided for information only and is not legal or tax advice. References are accurate as of 24 October 2026. Check current rules with a qualified professional before applying them to a specific vendor file.

A company registration number check on a U.S. vendor confirms that the entity named on each document exists in a state record and that its name, status and tax identifier agree across the file. There is no single national company register in the United States: companies are formed and recorded state by state, usually by the Secretary of State or an equivalent office, while the IRS issues the tax identifier. That split is the reason U.S. vendor files so often carry a name that is correct on one document and slightly wrong on another. This guide sets out which field is compared with which, what a mismatch looks like and what the reviewer does next.

Which identifier belongs to which entity?

In the U.S., the state file number identifies the legal entity in a state record, and the EIN identifies it for federal tax purposes; they are issued by different bodies and never substitute for each other. Write down which one each document shows before comparing anything.

An LLC formed in one state and registered as a foreign entity in a second state can legitimately have two state records. The check must say which record the contract relies on.

What does the cross-check matrix look like?

A U.S. vendor file needs at least seven cross-checks, each with a defined failure pattern. This is the core of the process.

Normalize before comparing. Strip "LLC", "Inc." and "Corp." for a first-pass match, then compare the full name including the form. "Inc." versus "Incorporated" is formatting. "LLC" versus "LP" is a different entity.

Which checks does the W-9 allow?

A Form W-9 is the vendor's own statement of its name and taxpayer identification number, so it is a document to verify, not a verification in itself. The IRS publishes Form W-9 as the "Request for Taxpayer Identification Number (TIN) and Certification" (IRS). Eligible payers can also use the IRS e-Services TIN Matching program, which compares the name and TIN on a W-9 with IRS records; enrollment rules apply and are set by the IRS. TIN Matching applies to U.S. payees on a W-9, not to foreign vendors on a W-8. A positive match shows that the name and number combination exists in IRS records. It does not show that the vendor is in good standing in its state, or that the bank account belongs to it.

What does each lookup prove?

State record lookups show the public record of the entity; they do not authenticate the PDF in front of you.

Beneficial ownership is a separate topic. FinCEN's Corporate Transparency Act page states that, under an interim final rule published on 26 March 2025, entities created in the United States and their beneficial owners are exempt from beneficial ownership information reporting (FinCEN). In practice, a U.S. vendor file cannot rely on a federal ownership filing; ownership evidence has to come from the vendor or from your own due diligence. Confirm the current position on FinCEN's page before relying on this, as the rule was issued as an interim measure.

Which mismatches are harmless and which are red flags?

A new bank account on an existing vendor, combined with a changed contact email, is the pattern most often tied to payment redirection. Treat it as an identity question, not a typo.

What do users ask about this check?

Users on specialized forums often ask two things. The first: "The W-9 name does not match the name on the state record, is the vendor lying?" Not necessarily. Line 1 of a W-9 is the name as shown on the tax return, which for a single-member LLC can be the owner, while the business name goes on line 2. The reviewer compares the combination of name and EIN with what the vendor's tax return would show and asks for clarification, not an accusation. The second: "Is there one place to look up any U.S. company?" No. You search the state where the vendor was formed, and the state where it operates if different.

How do you run the check step by step?

1. Extract name, state, file number, EIN and address from each document, keeping the document type next to each value.
2. Identify the formation state and search that state's entity record. Save the result with the date.
3. Compare each extracted value using the matrix above.
4. Classify each difference as formatting, alias (DBA) or identity.
5. For identity differences, contact the vendor through a channel from the state record or a prior contract, never from the document in question.
6. Record the decision and evidence in the vendor file.

For the document list, see our supplier onboarding documents checklist and the article on cross-document verification. The overall method is in the document verification guide.

How can the check be automated?

CheckFile compares the fields extracted from each document, such as legal name, entity number, EIN, address and account holder, with each other and with the register data you supply, and lists the differences for a reviewer. It does not decide that a document is authentic; it shows where the file is inconsistent so a person can act. See how document validation works and the pricing.

FAQ

What is a company registration number check in the U.S.?

It is a comparison of the entity name and file number on a document with the record kept by the state where the entity was formed. It confirms that the entity exists and what its public status is.

Is the EIN the same as the state file number?

No. The EIN comes from the IRS and identifies the entity for federal tax purposes; the file number comes from the state filing office. A vendor file should carry both and tie them to the same name.

Does a Secretary of State lookup prove the document is genuine?

No. It shows the public record of the entity. A forged certificate can still quote a real file number, so name, status, signer and bank account holder must also match.

How often should the check be repeated?

At onboarding, when the vendor changes bank details or address, and at each periodic review. Good standing can lapse, so an old certificate says little about today.