How you verify a tax ID depends on which ID it is and whose it is. The IRS does not offer a public lookup for another business's EIN, but most states let you check a sales tax permit, some let you check a resale certificate, and the EU and UK run official services for VAT numbers.
This article is educational information, not tax advice. Verification tools, eligibility rules and record-keeping expectations differ by agency and state, so confirm the current process with the agency before relying on it.
Which tax ID are you verifying?
Businesses carry several identifiers, and each one is checked in a different place.
| Identifier | Who can verify it | Where |
|---|---|---|
| Your own EIN | You | IRS transcript, notice or Letter 147C |
| Another business's EIN | Only payers filing information returns | IRS TIN Matching, or a signed Form W-9 |
| State sales tax permit | Anyone, where the state offers a lookup | The state revenue department |
| Resale or exemption certificate number | Sellers, where the state offers a lookup | The state revenue department |
| VAT number | Anyone | VIES for the EU, HMRC for the UK |
An EIN is not a sales tax permit, and neither one is a VAT number. A match on one says nothing about the others.
Can you look up someone else's EIN?
No, not through the IRS. The IRS page on EINs explains how to verify your own number and does not describe any public way to look up another business's EIN.
If a vendor or customer gives you an EIN, the usual approach is to collect a completed Form W-9 and keep it on file. If you file information returns, such as Forms 1099, the IRS TIN Matching program checks names against taxpayer ID numbers (see below).
How do you verify your own EIN?
The IRS lists three ways to confirm an EIN you already hold:
- Request an entity transcript through the IRS business tax transcript service.
- Download a digital CP575, the EIN Verification Notice, from your Business Tax Account if you are eligible.
- Call the IRS business and specialty tax line at 800-829-4933 and request Letter 147C, which confirms an EIN that was previously assigned.
These confirm your number to you. They are not a way to confirm a number to a customer without your involvement, and a vendor asking for proof of your EIN will usually accept a Letter 147C or a signed W-9.
What is the IRS TIN Matching program?
TIN Matching is a free IRS e-Services tool that checks a name and taxpayer ID number combination before an information return is filed. The IRS says it is only for payers and their authorized agents that submit information returns, and a payer must be listed in the IRS Payer Account File. Payers are added if they filed Forms 1099 within the last two years.
That makes it useful for a business that pays contractors and files 1099s. It is not a general-purpose tool for vetting a customer's tax ID.
How do you verify a sales tax permit?
Sales tax permits are administered by each state, so the lookup lives on the state's website, and what it returns varies. These are the tools the agencies describe, for nine of the largest states:
| State | What you can check | Source |
|---|---|---|
| California | A seller's permit, among other CDTFA accounts, through the online verification webpage | CDTFA |
| Texas | Whether a sales and use tax permit is active or inactive, by taxpayer number, EIN, name, city or ZIP. Results are capped at 200 taxpayers | Comptroller |
| Florida | Resale and exemption certificates, online, by phone at 877-357-3725, or in the FL Tax-Verify app for registered dealers | Department of Revenue |
| Washington | Reseller permit status in the Business Lookup by permit number or business name, plus a free service for submitting a file of customers' permits | Department of Revenue |
| Illinois | Whether a business is registered, and how, using "Verify a Registered Business" in MyTax Illinois. The seller is responsible for checking that a purchaser's reseller number is valid and active | Department of Revenue |
| Pennsylvania | An open dataset of active sales tax licenses and exemption and wholesaler certificates, refreshed monthly | data.pa.gov |
| Georgia | Georgia sales tax numbers in the Georgia Tax Center. It does not check state tax ID numbers, EINs, out-of-state numbers or Social Security numbers | Department of Revenue |
| North Carolina | Registries of active sales and use tax account numbers, and of direct pay permit and exemption certificate numbers | Department of Revenue |
New York and New Jersey do not describe a public verification tool on the department pages we reviewed. In those states, ask the department how to confirm a number, and rely on a complete certificate kept on file.
Tools change, so confirm that the page still works before you build a process around it. If you cannot find a lookup for another state, check the revenue department's site for a taxpayer search or certificate verification page, or ask the agency directly.
How do you verify a customer's resale or exemption certificate?
A resale certificate lets a buyer purchase without paying sales tax, so the seller is the one who needs to be able to support the sale if it is questioned. A practical routine:
- Collect a complete certificate before you make the tax-free sale. Missing fields are a common reason a certificate is rejected later.
- Check the buyer's permit or ID number with the state's lookup, where one exists.
- Save the certificate and a record of the check, with the date.
- Watch for expiry. Some states require certificates to be renewed or refreshed, and the rule is not the same everywhere.
Rules on how long a certificate stays valid and what counts as accepting it in good faith are set by each state. See the guides in our resale certificate library for state-specific forms and requirements.
How do you verify a VAT number?
VAT numbers are issued by each country, so each country or region has its own check.
- EU numbers. Use VIES, the European Commission's validation service. Our free VAT number checker looks EU numbers up in VIES for you.
- UK numbers. HMRC runs the official service for checking a UK VAT number, and our checker points UK numbers to it.
- Everywhere else. Use the tax authority in the country that issued the number.
A valid result confirms that the number is registered. It does not confirm the buyer's name or address, and it does not decide how a transaction is taxed. For number formats by country, see What is a VAT number?. If you are a US business asking whether you need one, see Do US companies have a VAT number?.
What if a tax ID does not verify?
A failed check does not always mean fraud. Common causes include:
- A typo or a transposed digit.
- A registration that is new and not yet in the agency's system.
- A permit that has been closed, suspended or has lapsed.
- A mismatch between a legal name and a trade name.
- A number that belongs to a different kind of account, such as an EIN entered where a sales tax permit number is expected.
Ask the customer for a corrected number or certificate rather than guessing. If the sale is time-sensitive, collect tax until the certificate is confirmed, and refund it once a valid certificate is on file if your state allows that.
What should you keep on file?
Keep the evidence that shows what you checked and when:
- The certificate, Form W-9 or number provided, as received.
- A screenshot or saved result of the lookup, with the date.
- The invoice or order it relates to.
- Any follow-up correspondence about a number that did not match.
Software that manages exemption certificates, such as Kintsugi, can store these records and request missing certificates from customers, which is easier than tracking them in a spreadsheet once the number of customers grows.
Frequently asked questions
Is there a free EIN lookup?
Not from the IRS for other businesses. The IRS explains how to verify your own EIN, and TIN Matching is limited to payers that file information returns. To confirm a vendor's number, ask for a signed Form W-9.
How do I confirm my own EIN?
Request an entity transcript, download a CP575 from your Business Tax Account if you are eligible, or call the IRS business and specialty tax line at 800-829-4933 and ask for Letter 147C.
Can I verify a customer's sales tax ID?
In many states, yes. California, Texas and Florida all publish tools for checking permits or certificates, and other states have their own. Where a state has no lookup, rely on a complete certificate and keep it on file.
Is an EIN the same as a sales tax ID?
No. An EIN identifies a business for federal tax purposes. A sales tax permit or ID is issued by a state and authorizes a business to collect sales tax there.
Does verifying a number protect me in an audit?
It helps you document that you checked, which is useful evidence if a state questions a tax-free sale. Whether it is enough depends on the state's rules for accepting certificates in good faith, so follow the state's guidance.
