TIN ComplianceA resource from TIN Comply
Reference

What is a TIN number? SSN, ITIN, EIN and the others, explained

A taxpayer identification number (TIN) is the nine-digit number the IRS uses to tie income to a taxpayer. It is not one kind of number: an individual’s TIN is usually a Social Security number, a business’s is an Employer Identification Number, and people who cannot get an SSN use an ITIN. Which one you have decides which name goes with it, and that pairing is what every 1099 and W-9 turns on.

Who this is for anyone asked for a TIN on a form, and anyone collecting themUpdated September 22, 2026Sources IRS “Taxpayer Identification Numbers” page; Form W-9 and W-7 instructions; SSA

The five kinds of TIN

NumberIssued byFormatWho has oneGoes with
SSN Social Security numberSocial Security Administration###-##-####; first digit never 9; no 000, 666 or 900–999 area; no 00 group; no 0000 serialU.S. citizens and people authorized to work in the U.S.The individual’s own name
ITIN Individual Taxpayer Identification NumberIRS (Form W-7)9##-##-####; fourth and fifth digits 50–65, 70–88, 90–92 or 94–99People with a U.S. tax filing need who cannot get an SSNThe individual’s own name
EIN Employer Identification NumberIRS (Form SS-4 or online)##-#######; the first two digits come from a fixed set of prefixesBusinesses, trusts, estates, nonprofits, and sole proprietors who want oneThe legal name the IRS assigned it to
ATIN Adoption TINIRS (Form W-7A)Nine digitsA child in a pending domestic adoption, temporarilyThe child’s name
PTIN Preparer TINIRSP########Paid tax return preparersThe preparer, on returns they sign; never on a W-9

ITIN vs SSN

Both are nine-digit numbers for individuals, and both are “TINs” on a W-9. The differences are who issues them and what they mean.

SSNITIN
IssuerSocial Security AdministrationIRS
Who qualifiesCitizens, permanent residents, and non-citizens authorized to workAnyone with a U.S. tax obligation who is not eligible for an SSN: certain nonresident aliens, dependents and spouses, foreign investors
Work authorizationUsually implies itNever. An ITIN is for tax reporting only
ExpirationNeverExpires if not used on a federal return for three consecutive years; renew with Form W-7
How to spot itFirst digit 0–8First digit 9, with the group digits in the ITIN ranges
On a W-9Individual’s name, SSN boxIndividual’s name, same box
For the payerTIN matching validates against SSA recordsTIN matching validates against IRS records; an expired ITIN still matches for information-return purposes

A person who later becomes eligible for an SSN must stop using the ITIN and tell the IRS so the records are merged; a W-9 with the old ITIN will keep matching for a while and then start failing.

EIN, FEIN and “tax ID”: the same thing

An EIN, a FEIN (Federal EIN), a federal tax ID number and an employer ID all mean the same nine digits. A state tax ID is different: states issue their own numbers for sales tax, withholding and unemployment, and none of them belongs on a W-9 or a 1099. An EIN is issued to a specific legal name (the one on the CP 575 notice or a Letter 147C) and matches only that name. A sole proprietor’s EIN is issued to the person, so the person’s name is still the one that matches; the LLC and sole proprietor guide works through the cases.

Where to find yours

  • SSN: your Social Security card; your W-2 (box a); your tax return. The SSA does not give it out by phone.
  • ITIN: the IRS CP565 assignment notice; your tax return.
  • EIN: the CP 575 notice; prior business returns; bank paperwork; or call the IRS for a Letter 147C. For someone else’s EIN, see how to find a company’s EIN.

Which TIN goes on the W-9

Foreign TINs

A foreign payee does not need a U.S. TIN to be paid, but a W-8BEN generally must show either a U.S. TIN or the payee’s foreign tax identification number (FTIN) from their home country, with a reason if there is none. The FTIN is not matched against IRS records; it is reported on Form 1042-S. Details in the foreign vendors guide.

Questions people ask

Is a TIN the same as an EIN?

An EIN is one kind of TIN. “TIN” is the umbrella term; SSNs, ITINs, EINs, ATINs and PTINs are all TINs.

Can I look up someone’s TIN?

Not an individual’s. Business EINs appear in SEC filings and nonprofit Form 990s, and commercial databases index them; the only way to confirm a name/TIN pair is the IRS TIN Matching Program, and only payers can use it.

Can a company use a TIN with a dash?

On paper forms, yes. In electronic filing and TIN matching the number is nine digits with no punctuation, which is why hyphens are the most common format error. Check with the format checker.

What is a “TIN number”?

The same thing; the N already stands for number. The phrase is common enough that the IRS uses it too.