Taxpayer identification number (TIN): what your tax ID is and where to find it

By the HRPricing editorial teamReviewed October 18, 2026How we research and score

A taxpayer identification number (TIN) is the number used to identify you or your business on U.S. tax returns and forms: a Social Security number (SSN) for most people, an employer identification number (EIN) for businesses, or an ITIN, ATIN or PTIN in special cases. The Social Security Administration issues SSNs and the IRS issues every other type (IRS TIN page, checked October 18, 2026).

Taxpayer identification number (TIN) is the umbrella term for the IDs used in U.S. tax administration: the SSN, EIN, ITIN, ATIN and PTIN.

On this page
  1. The five types of TIN
  2. Which number you need as an employer
  3. Example: a contractor who will not give you a TIN
  4. Where to find your TIN

The five types of TIN

Taxpayer identification numbers and how to get them
TypeIssued byWho uses itHow to apply
SSNSocial Security AdministrationU.S. citizens and people with work authorizationForm SS-5, free
EINIRSBusinesses and employers; estates and trusts filing Form 1041Form SS-4
ITINIRSCertain resident and nonresident aliens, spouses and dependents who cannot get an SSN. Nine digits starting with 9Form W-7, usually with a tax return
ATINIRSParents adopting a child whose SSN will not arrive in time to fileForm W-7A
PTINIRSPaid tax preparers (required since January 1, 2011)Online, or Form W-12 (4 to 6 weeks on paper)

Source: IRS, Taxpayer Identification Numbers (TIN), last reviewed June 11, 2026, checked Oct 18, 2026.

Which number you need as an employer

To run payroll you need an EIN. It goes on every Form 941, Form 940 and W-2 you file, and on new hire reports, which also need each employee's name, address and SSN and are due to the state within 20 days of hire (sooner in states such as Alabama and Maine, 7 days). The steps are in our payroll setup guide and the first employee checklist.

If you join a certified PEO, it reports wages under its own EIN. The IRS warns that many CPEO names look alike, so check the exact name and EIN on the contract against the IRS certified PEO list. With an ASO your own EIN stays on everything (PEO vs ASO).

Example: a contractor who will not give you a TIN

Ask every contractor for a Form W-9 with a TIN before the first payment. From 2026, Form 1099-NEC reporting starts at $2,000 a year (it was $600), and the backup withholding threshold rose to $2,000 with it. If you pay a contractor $5,000 in 2026 and they never give you a TIN, you withhold 24% backup withholding: $1,200, which you deposit and report to the IRS. More on paying contractors and W-2 vs 1099 status.

Where to find your TIN

  • SSN: your Social Security card, or any W-2 you received.
  • Your employer's EIN: printed on your W-2.
  • Your business EIN: on the IRS letter that assigned it and on any Form 941 or business return you filed.

Frequently asked questions

What is a taxpayer identification number?
It is the ID used on U.S. tax returns and forms: a Social Security number, an EIN, an ITIN, an ATIN or a PTIN. The SSA issues SSNs and the IRS issues the rest (IRS TIN page, checked October 18, 2026).
Is my tax ID number the same as my Social Security number?
For most individuals, yes: the SSN is their taxpayer identification number. People who cannot get an SSN use an ITIN, a nine-digit IRS number that starts with 9, issued through Form W-7.
What is a tax ID number for a business?
A business uses an employer identification number (EIN), issued by the IRS through Form SS-4. Any business with employees needs one to file Forms 941, 940 and W-2.
What is a US taxpayer ID number for a non-citizen?
A non-citizen authorized to work in the U.S. gets an SSN. One who must file taxes but cannot get an SSN applies for an ITIN on Form W-7 (IRS TIN page).
What happens if a contractor does not give me a TIN?
You must apply 24% backup withholding to reportable payments once they reach the 2026 threshold of $2,000, per IRS Publication 15 (2026). On a $5,000 payment that is $1,200.
Sources (5)
  1. IRS: Taxpayer Identification Numbers (TIN) (checked Oct 18, 2026)
  2. IRS: Publication 15 (2026), Employer's Tax Guide (checked Oct 16, 2026)
  3. IRS: Instructions for Forms 1099-MISC and 1099-NEC (Dec 2026) (checked Oct 16, 2026)
  4. Cornell LII (U.S. Code text): 42 USC 653a, State Directory of New Hires (checked Oct 16, 2026)
  5. IRS: Certified Professional Employer Organization (checked Oct 16, 2026)

This page is general information, not tax, legal or accounting advice. Rules and rates change, so check the official source linked above before you file or sign a contract. Read our disclaimer.