To verify a tax ID number, match it against the issuing agency’s records using the tool that fits your situation: the IRS TIN Matching program for EINs and for SSNs or ITINs collected on a Form W-9, the Social Security Administration’s Number Verification Service for employee SSNs used in W-2 reporting, and the SSA’s Consent Based SSN Verification for banks and other financial institutions. There is no single public lookup that returns a name from a number, and federal law restricts most verification channels to specific purposes.1Office of the Law Revision Counsel. 26 USC 6103 – Confidentiality and Disclosure of Returns and Return Information Getting a match matters: a bad name/TIN combination on an information return can trigger backup withholding at 24% and per-return penalties starting at $60.
Start With a Signed W-9
Before you verify anything, get the number in writing. Ask the vendor, contractor, or payee for a completed Form W-9, Request for Taxpayer Identification Number and Certification. The payee fills in their legal name, entity type, and TIN, then signs under penalty of perjury that the information is correct.2Internal Revenue Service. Instructions for the Requester of Form W-9 (Rev. March 2024) That signed form is your record linking a name to a number, and it protects you if a mismatch surfaces later.
Foreign payees do not use W-9. If you are paying a nonresident alien individual or a foreign entity, you collect a W-8 form instead, and the standard TIN Matching program does not cover them. Your compliance obligation for foreign payees centers on getting a properly completed W-8 and applying the correct withholding rate, not on running the number through an IRS matching tool.3Internal Revenue Service. Instructions for Form W-8BEN-E
Use IRS TIN Matching for EINs and Contractor TINs
The IRS TIN Matching program is a free e-service open to anyone who files information returns subject to backup withholding. It confirms whether a name and TIN on a W-9 match IRS records. It is a pass/fail check: the pair either matches or it doesn’t, and the system tells you nothing else about the payee.4Internal Revenue Service. Taxpayer Identification Number (TIN) Matching Tools
You have to register through the IRS e-Services portal before you can use it. Once enrolled, you can run checks two ways. Interactive TIN Matching accepts up to 25 name/TIN combinations at a time with immediate results, capped at 999 requests in a 24-hour period. Bulk TIN Matching lets you upload a file with up to 100,000 combinations and returns results within 24 hours, which suits payroll processors or larger companies verifying an entire vendor list.4Internal Revenue Service. Taxpayer Identification Number (TIN) Matching Tools
One timing detail catches people off guard: the IRS advises waiting at least two weeks after an EIN is issued before running it through TIN Matching, because new EINs need time to propagate.5Internal Revenue Service. Employer Identification Number A mismatch on a brand-new vendor may just be a timing problem.
An expired ITIN is another common cause of unexpected mismatches. Any ITIN not used on a federal tax return for three consecutive tax years expires on December 31 of that third year, and the payee has to renew it with the IRS before the number will match again.6Internal Revenue Service. How to Renew an ITIN
The IRS does not maintain a public EIN lookup where you can type in a number and pull up who owns it. TIN Matching is as close as you get, and it only works if you already have both the name and the number from the payee.
Verify Employee SSNs Through the SSA
For W-2 wage reporting, the Social Security Administration runs its own free tool, the Social Security Number Verification Service. You submit up to 10 name/SSN pairs online for immediate results, or upload a file of up to 250,000 names for overnight processing.7Social Security Administration. The Social Security Number Verification Service
The service is strictly limited to wage reporting. You cannot use it for pre-employment screening, and only current or former employees are eligible for verification.8Social Security Administration. Social Security Number Verifications For independent contractors who gave you an SSN or ITIN on a W-9, this SSA tool is off-limits; use IRS TIN Matching instead.
Consent-Based SSN Verification for Financial Institutions
Banks, mortgage companies, and other lenders that need to verify a customer’s SSN outside the employment context can use the SSA’s Consent Based SSN Verification service. CBSV checks whether a name, date of birth, and SSN match SSA records, but only with the SSN holder’s written consent, typically documented on Form SSA-89.9Social Security Administration. Consent Based Social Security Number Verification (CBSV) Service
CBSV is not cheap. Enrollment costs a one-time $5,000 fee, and each verification is $2.25. The service does not verify identity or citizenship, so it will not satisfy I-9 requirements or replace know-your-customer checks.
The One Public Database: Tax-Exempt Organizations
If you are verifying a nonprofit before making a deductible donation or issuing payment, the IRS Tax Exempt Organization Search is publicly available at no cost. You can look up a charity by name or EIN and confirm its exempt status.10Internal Revenue Service. Tax Exempt Organization Search11Internal Revenue Service. Tax Exempt Organization Search This is the only situation where the IRS lets you look up a TIN without already having it in hand.
Validation Is Not Verification
These two words describe different checks, and confusing them leaves you exposed. Validation is a format check. It confirms the number has the right structure: nine digits for an EIN, nine digits in SSN format, an ITIN that starts with 9 and has middle digits in the allowed ranges.12Internal Revenue Service. IRS Individual Taxpayer Identification Number (ITIN) Real-Time System (RTS) Validation catches typos and obviously wrong formats.
Verification confirms the number actually belongs to the person or entity claiming it. A stolen SSN passes validation because the format is correct; it only fails verification when the name attached to it does not match the issuing agency’s records. That is why TIN Matching and the SSA services exist. They link a number to a name, which is the check that actually protects you.4Internal Revenue Service. Taxpayer Identification Number (TIN) Matching Tools
What Happens If a TIN Doesn’t Match
File an information return with a name/TIN combination that doesn’t match IRS records, and the IRS sends you a CP2100 or CP2100A notice identifying the mismatched accounts. That starts the B-Notice process, and the deadlines are tight.
For a first-time mismatch on a given payee, you send the payee a First B-Notice along with a blank Form W-9. The payee must give you a corrected TIN. If they do not respond, you must begin backup withholding on future payments. If the same payee shows up on a CP2100 or CP2100A a second time within three years, you send a Second B-Notice, and this time a fresh W-9 is not enough. The payee has to provide a copy of their Social Security card or an IRS Letter 147C confirming their EIN before you can stop withholding.13Internal Revenue Service. Backup Withholding “B” Program
If a TIN is missing entirely or obviously wrong, you do not wait for a B-Notice. Backup withholding starts immediately on those payments. Once the payee gives you a corrected TIN, you stop withholding within 30 calendar days.14Internal Revenue Service. Understanding Your CP2100 or CP2100A Notice
Backup Withholding and Filing Penalties
When backup withholding applies, you deduct 24% from reportable payments and remit it to the IRS. The liability for failing to withhold when required falls on you as the payer, not the payee: if you should have been withholding and weren’t, you owe the IRS the amount you failed to collect.15Office of the Law Revision Counsel. 26 USC 3406 – Backup Withholding Backup withholding kicks in when the payee fails to provide a TIN, when the IRS notifies you the TIN is incorrect, when there has been notified payee underreporting, or when the payee fails to certify they are not subject to backup withholding.
Separate from withholding, Section 6721 imposes per-return penalties for filing information returns with incorrect or missing TINs. For returns required to be filed in 2026:16Internal Revenue Service. Information Return Penalties
- Corrected within 30 days: $60 per return
- Corrected by August 1: $130 per return
- Not corrected or filed after August 1: $340 per return
- Intentional disregard: $680 per return
These penalties apply both to the return filed with the IRS and to the payee statement, so a single bad TIN can generate two penalties for the same transaction. For a business filing hundreds of 1099s, a systematic problem gets expensive quickly. Collecting signed W-9s, running the names through TIN Matching before you file, and acting on any CP2100 within its deadline is what keeps that from happening.