How to look up and verify a company’s EIN (tax ID)

There is no free public tax ID lookup from the Internal Revenue Service (IRS) that shows another company’s Employer Identification Number (EIN), except for tax-exempt organizations. To find a business’s EIN, check its Securities and Exchange Commission (SEC) filings if it’s a public company, use the IRS Tax Exempt Organization Search if it’s a nonprofit, or — for most private companies — ask the business for its IRS EIN letter and a signed Form W-9.

To verify the number, compare those documents with each other and with state records. If you pay a business and file certain Forms 1099 for it, the IRS Taxpayer Identification Number (TIN) Matching program can also check its name and EIN before you file. And if you’ve lost your own EIN, the IRS will give it to you by phone once it confirms you’re authorized.

What is an EIN?

The IRS describes an EIN as “a federal tax ID number for businesses, tax-exempt organizations and other entities” on its Employer Identification Number page. It’s a nine-digit number in the format XX-XXXXXXX, according to IRS Publication 1635. You’ll also hear it called a federal tax ID, a business tax ID or, on forms like the W-9, a taxpayer identification number.

Two IRS rules matter when you check one. The IRS says “a business entity should have only one EIN,” and that a business generally needs a new EIN when its ownership or structure changes — but not when it changes its name, address or responsible party (IRS EIN guidance). So a name that differs from an older IRS letter isn’t automatically a problem. It is a question worth asking.

Is there a public tax ID lookup?

Not for most businesses. The IRS’s EIN guidance explains how an owner can find or confirm their own number. It does not offer a search for other companies’ EINs. Federal tax law also bars the IRS from disclosing “returns and return information” unless the tax code authorizes it, and return information includes a taxpayer’s identity, as the Internal Revenue Manual’s introduction to disclosure explains.

What does exist is narrower: SEC filings for public companies, an IRS search for tax-exempt organizations, and TIN Matching for eligible payers — each covered below. Paid “EIN lookup” websites are not IRS services. Treat anything they return as a lead to confirm with the business, not as proof.

How to look up a company’s EIN

If you’re working out how to look up an EIN number for a business you’re onboarding, the answer depends on what kind of business it is.

Public companies: SEC filings

The cover page of a Form 10-K annual report has a field for the company’s “I.R.S. Employer Identification No.,” right beside its state of incorporation. Find the company on EDGAR, the SEC’s online filing system, open a recent 10-K, and the EIN is on the first page.

Nonprofits: IRS Tax Exempt Organization Search

The IRS Tax Exempt Organization Search lets you search by EIN or organization name. According to the IRS description of the tool, it covers Publication 78 data, the automatic revocation list, determination letters, Form 990-series returns and Form 990-N (e-Postcard) filings. The same page warns users to expect delays in data updates, so a newly recognized organization may not show up yet.

Private companies: ask the business

For most private companies, the reliable source is the company itself. Ask for two things:

• The IRS EIN letter. The original letter is a CP 575 notice, which the IRS’s CP 575 notice page calls the “Notice of New Employer Identification Number.” A business that has lost the original can call the IRS and request Letter 147C, “EIN Previously Assigned,” or an eligible user can download a digital CP 575 from IRS Business Tax Account, which the IRS says can be used in place of the original CP 575 and Letter 147C.
• A signed Form W-9. The IRS instructions for requesters of Form W-9 say the form is used to request the TIN of a U.S. person, and a valid form is signed and dated under penalties of perjury.

State business records

Don’t count on a state registry for the tax ID. Delaware’s free entity search, for example, lists the entity name, file number, formation date, registered agent and residency — no EIN. Use state records to confirm the exact legal name you’re matching the EIN against.

Reverse EIN lookup: who owns this number?

A reverse EIN lookup starts with the number and asks who it belongs to. For public companies, the EDGAR full-text search help page says the tool covers all EDGAR filings submitted electronically since 2001 and matches words in quotation marks as an exact phrase. Searching the EIN in quotes — with and without the hyphen — may surface a filing that names the company. Tax Exempt Organization Search also accepts an EIN, so you can check whether a number belongs to a listed nonprofit.

For a private company, there’s no public reverse lookup, and TIN Matching won’t help because it checks a name and number you supply. If an applicant’s EIN turns up in another company’s SEC filing or nonprofit record, stop and ask why.

How to verify an EIN number

Verifying an EIN means confirming that the number belongs to the business in front of you. For most companies, that’s a careful document comparison:

1. Match the legal name across sources. The name on the IRS letter, the W-9 and the state record should agree, apart from changes the business can document.
2. Look at the whole letter. Ask for the full CP 575 or 147C, not a cropped image of the number. The IRS says the original CP 575 “cannot be duplicated or recreated” (IRS CP 575 page), so a business that lost it should get a 147C or a digital CP 575 rather than a reprint.
3. Get a signed W-9. The signature puts the business’s certification that its TIN is correct on record, under penalties of perjury (Form W-9 requester instructions).

How to verify an EIN number online

The IRS tool for this is TIN Matching, which lets a payer that files information returns “match TIN and name combinations with IRS records” before filing, as the Form W-9 requester instructions describe it. It isn’t open to everyone. The IRS’s TIN Matching page says it is “only for payers and their authorized agents that submit information returns” and that the payer must be listed in the IRS Payer Account File, which adds payers “if they filed Forms 1099 within the last 2 years to report backup withholding.” You also need an IRS online account to apply. The IRS’s TIN on-line matching page says interactive matching accepts up to 25 name/TIN pairs on screen and bulk matching up to 100,000 in a text file.

TIN Matching is a tax-reporting tool, not an onboarding check. The federal tax regulation that governs it, 26 CFR 31.3406(j)-1, keeps matching results confidential and says a payer “may not take into account” them “in determining whether to open or close an account with a payee.”

Online marketplaces have a specific rule. Under the INFORM Consumers Act, a marketplace must collect a business tax ID (or a taxpayer identification number, if the seller has none) from high-volume third-party sellers and verify it within 10 days, according to the Federal Trade Commission’s (FTC’s) INFORM Act guidance. The same FTC guidance says information in a valid government-issued tax document can be presumed verified as of that document’s date — one more reason to ask for the IRS letter itself.

How to find your own EIN

If you’re asking “how do I look up my EIN number?”, start with your own paperwork. The IRS’s lost or forgot EIN steps are:

1. Look for the notice the IRS sent when you applied for the EIN.
2. Contact the bank that holds your business account.
3. Check with agencies where you applied for state or local licenses.
4. Look on past business tax returns.
5. If you still can’t find it, call the IRS at 800-829-4933, Monday to Friday, 7 a.m. to 7 p.m. local time (Alaska and Hawaii follow Pacific time). The IRS will verify your identity and give you the number over the phone if you’re authorized to receive it.

If a bank or partner wants written proof, the IRS lists three ways to confirm an EIN: request an entity transcript, download a digital CP 575 from Business Tax Account, or call and request Letter 147C. In Business Tax Account, the notice is under Tax Records. And as the IRS’s EIN application page puts it, “You never have to pay a fee for an EIN” — so be wary of websites that charge for one.

Red flags when checking a tax ID

• The name doesn’t match. The IRS letter, W-9, state record and bank account show different legal names, and the business can’t document a name change.
• Letter details don’t line up. The name, address or entity type on the IRS letter conflicts with the state filing or the W-9, or the letter looks edited.
• The number belongs to someone else. The EIN appears in a different company’s SEC filing or nonprofit record.
• A number without a signature. The business gives you an EIN but won’t sign a W-9 certifying it.
• More than one EIN with no explanation. The IRS says a business entity should have only one.

None of these proves fraud on its own. Each is a reason to ask for more documents before you approve the account.

Where EIN checks fit in business verification

An EIN check is one step of know your business (KYB) verification, not the whole thing. For banks, the customer identification program (CIP) rule at 31 CFR 1020.220 requires a taxpayer identification number for a U.S. person before an account is opened, along with a name and, for a business, a principal place of business or other physical location. For more on CIP, see our guide to remote account opening and CIP basics.

A full business check pairs the EIN documents with formation records, the owners’ identities and sanctions screening. With Securely Verify’s document collection, you can request the CP 575 or 147C letter, formation documents and a voided check through one secure link. Business verification, on Growth plans and up, then sends an identity check to each owner and keeps everything in one case. It does not check EINs against IRS records, so the match still rests on the documents and your reviewer’s judgment. Confirm with your compliance team which checks your own rules require.

If you want to try this on your own business customers, start a 7-day free trial — 20 verifications, no card required.

Related guides

• What is KYB? A plain-English guide to know your business checks
• Merchant onboarding: how to verify a merchant and its owners
• Proof of address: what documents count and how to verify them

Sources: Employer identification number (IRS, updated July 17, 2026); Publication 1635, Understanding Your EIN (IRS, rev. February 2014); Internal Revenue Manual 11.3.1, Introduction to Disclosure (IRS, August 3, 2023); Form 10-K (SEC, rev. February 2025); EDGAR Full-Text Search frequently asked questions (SEC, accessed October 16, 2026); Tax Exempt Organization Search (IRS, accessed October 16, 2026); Tax Exempt Organization Search tool (IRS, accessed October 16, 2026); Understanding your CP575 notice (IRS, updated June 16, 2026); Business Tax Account (IRS, updated October 16, 2026); Instructions for the Requester of Form W-9 (IRS, rev. March 2024); Taxpayer Identification Number (TIN) Matching (IRS, updated August 10, 2026); Taxpayer identification number (TIN) on-line matching (IRS, updated June 18, 2026); 26 CFR 31.3406(j)-1, Taxpayer Identification Number (TIN) matching program (Electronic Code of Federal Regulations, current as of October 14, 2026); Informing Businesses about the INFORM Consumers Act (FTC, June 2023, edited January 2025); Entity Search (Delaware Division of Corporations, accessed October 16, 2026); Get an employer identification number (IRS, updated October 16, 2026); 31 CFR 1020.220, Customer identification program requirements for banks (Electronic Code of Federal Regulations, current as of October 14, 2026). This article is general information, not legal or compliance advice.