US TIN Format Validator
Validate the format of a US TIN, either an SSN (individuals) or EIN (businesses). Check American tax identification numbers in your records.
Result
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US TIN (Taxpayer Identification Number): the umbrella over SSN, ITIN, EIN and more
A Taxpayer Identification Number (TIN) is not a single format — it's the IRS umbrella term for any number used to identify a taxpayer on a federal return. Every TIN is 9 digits, but the grouping and issuing authority depend on which type it is:
- SSN —
XXX-XX-XXXX, issued by the SSA to individuals. The most common TIN. - ITIN —
9XX-XX-XXXX(starts with 9, group 70–99), issued by the IRS to individuals ineligible for an SSN. - EIN —
XX-XXXXXXX, issued by the IRS to businesses and entities. - ATIN — Adoption Taxpayer Identification Number, a temporary number for a child being adopted before an SSN is available.
- PTIN — Preparer Tax Identification Number (
P+ 8 digits), required for paid tax-return preparers.
This validator checks that a value matches one of the recognized TIN shapes. Because the grouping differs (3-2-4 for SSN/ITIN vs 2-7 for EIN), the position of the hyphen often tells you which type you're looking at.
Why "TIN" appears on so many forms
US tax forms ask for a TIN rather than a specific type because the right one depends on the filer: an employee provides an SSN on a W-4, a foreign contractor provides an ITIN on a W-8BEN, and a company provides an EIN on a W-9. The IRS's TIN Matching program lets payers verify that a name+TIN pair matches IRS records before filing 1099s — reducing backup-withholding penalties.
Common pitfalls
- No universal checksum: none of the TIN types has an arithmetic check digit; validation is structural plus IRS records.
- Picking the wrong type: submitting an SSN where an EIN is required (or vice versa) causes IRS mismatches and B-notices.
- Format ≠ a real match: only IRS TIN Matching confirms the name+number pair is valid.
FAQ
Is a TIN the same as an SSN? An SSN is one kind of TIN. TIN is the broader category that also covers ITIN, EIN, ATIN and PTIN.
How many digits is a TIN? Nine for SSN/ITIN/EIN/ATIN; a PTIN is the letter P plus 8 digits.
Can I verify a TIN online? Authorized payers can use IRS TIN Matching to confirm a name+TIN pair; this tool only validates the format.
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