Free tool
TIN format checker for EINs, SSNs & ITINs
Catch impossible taxpayer ID numbers before they end up on a 1099 or W-2. Check one number or paste a whole column from your spreadsheet.
Runs entirely in your browser. Nothing you enter is sent to us or stored.
Short answer
A TIN can only be valid if its format is possible. An SSN (XXX-XX-XXXX) never starts with 000, 666 or 900–999 and never has 00 in the middle or 0000 at the end. An ITIN starts with 9 and has 50–65, 70–88, 90–92 or 94–99 as its 4th and 5th digits; an ATIN is 9XX-93-XXXX. An EIN (XX-XXXXXXX) must start with a prefix the IRS assigns, so it never starts with 00, 07–09, 17–19, 28–29, 49, 69–70, 78–79, 89 or 96–97. A correct format doesn't prove the number belongs to the payee: only IRS TIN Matching confirms the name and TIN together.
- SSNs have been assigned at random since June 25, 2011
- ITIN ranges per IRS Publication 1915
- EIN prefixes per the IRS valid EIN prefix list (updated April 2026)
- Wrong TINs lead to CP2100 notices, B notices and 24% backup withholding
Last reviewed against IRS Publication 1915, the IRS valid EIN prefix list and SSA's SSN randomization notice.
| Line | Entered | Result | Type | Notes |
|---|
The four kinds of TIN, in plain English
A Taxpayer Identification Number (TIN) is the number the IRS uses to tie income to a person or business. Every 1099, W-2 and 1095 you file carries one for you (the payer) and one for each recipient. There are four you'll run into:
| TIN | Written as | Who gets one | Issued by |
|---|---|---|---|
| SSN Social Security number | XXX-XX-XXXX | U.S. citizens and people authorized to work in the U.S. | Social Security Administration |
| EIN Employer Identification Number | XX-XXXXXXX | Corporations, partnerships, LLCs, nonprofits, trusts, estates, and any business with employees. Sole proprietors may get one too. | IRS |
| ITIN Individual Taxpayer Identification Number | 9XX-XX-XXXX | People who have a U.S. tax filing requirement but aren't eligible for an SSN. | IRS |
| ATIN Adoption Taxpayer Identification Number | 9XX-93-XXXX | Children in a pending U.S. adoption, temporarily, until they get an SSN. | IRS |
What the checker looks for
Social Security numbers
Since June 25, 2011 the SSA has assigned SSNs at random, so you can no longer tell where or when someone got theirs. But some combinations have never been issued and never will be:
- The first three digits are never 000, 666, or anything from 900 to 999.
- The middle two digits are never 00.
- The last four digits are never 0000.
- A few famous numbers, like the 078-05-1120 printed on sample cards inside wallets sold by Woolworth and other stores from 1938, have been voided.
ITINs and ATINs
Both always start with 9. For an ITIN, the 4th and 5th digits fall in the ranges 50–65, 70–88, 90–92 or 94–99. An ATIN always has 93 in that spot.
Employer Identification Numbers
The first two digits of an EIN, its prefix, originally showed which IRS campus issued it. The IRS publishes the list of prefixes it uses, and a handful have never been assigned:
Never used: 00, 07, 08, 09, 17, 18, 19, 28, 29, 49, 69, 70, 78, 79, 89, 96, 97
An EIN with one of those prefixes is a typo or made up. The checker also flags numbers where every digit is the same, or that run in sequence, since these are almost always placeholders someone typed to get past a required field.
Why a bad TIN costs you money
When you e-file information returns, the IRS compares each recipient's name and TIN with its records. Mismatches come back to you later, often months after you filed, as a CP2100 or CP2100A notice. From there:
- You have to send each listed payee a "B notice" and a fresh Form W-9, generally within 15 business days of getting the IRS notice.
- If the payee doesn't give you a corrected TIN, you're required to start backup withholding: holding back 24% of future payments and sending it to the IRS.
- Separately, the IRS can charge information return penalties for each form filed with a missing or incorrect TIN, with the amount growing the longer it goes uncorrected.
Most of that is avoidable. The cheapest fix is getting a correct W-9 before you pay anyone, and checking it before you file.
A simple TIN routine for 1099 season
- Collect a W-9 before the first payment. It's far easier to get one while the vendor is waiting on your check. With EFileForMe you can email a secure link so the payee fills in the W-9 online and it lands on their recipient record.
- Run this format check on your vendor list. Paste the TIN column and download the CSV of anything flagged.
- Run IRS TIN Matching on the ones that pass, to confirm name and number belong together.
- Use the exact name the IRS has. For a sole proprietor using their SSN, that's the person's name, not their trade name. For a single-member LLC, it's usually the owner.
- File early. 1099-NEC is due January 31. See every date on our filing deadlines page.
Related tools
- Name and TIN won't match? Work out the IRS name control.
- Collecting TINs: W-9 request letter and how to fill out a W-9.
- Checking a whole vendor file: the 1099 vendor list checker.
- Got a mismatch notice? The CP2100 and B notice guide and backup withholding.
Sources
- IRS: How EINs are assigned and valid EIN prefixes
- IRS Publication 1915, Understanding Your ITIN (ITIN number ranges)
- IRS: Adoption Taxpayer Identification Number (ATIN)
- SSA: Social Security Number randomization (June 25, 2011)
- SSA History: Social Security numbers that were misused (078-05-1120)
- IRS Publication 1281, Backup Withholding for Missing and Incorrect Name/TINs
- IRS: Information return penalties
- IRS: Taxpayer Identification Number (TIN) Matching
Questions
TIN questions
Does this tool tell me if a TIN is real?
No. It tells you whether a number is structured the way the IRS and Social Security Administration issue them. A number can pass and still belong to someone else, or to no one. Only IRS TIN Matching, which compares the name and number against IRS records, can confirm that a name and TIN belong together.
Is it safe to type Social Security numbers into this page?
Yes. The checker is a small script that runs in your own browser. Nothing you type or paste is sent to EFileForMe or anyone else, it isn't saved, and it's gone when you close or reload the page. You can even disconnect from the internet after the page loads and it will keep working.
What's the difference between an SSN, an ITIN and an EIN?
All three are nine-digit Taxpayer Identification Numbers. An SSN (XXX-XX-XXXX) is issued by the Social Security Administration to individuals. An ITIN (also XXX-XX-XXXX, always starting with 9) is issued by the IRS to people who need to file taxes but can't get an SSN. An EIN (XX-XXXXXXX) is issued by the IRS to businesses, trusts, estates and other entities, and to sole proprietors who choose to use one.
Which TIN should a contractor give me?
Whichever one they file their own taxes under, and the name on the W-9 has to match it. A sole proprietor can give either their SSN or their business EIN, but with an SSN the name line must be their personal name. A single-member LLC that hasn't elected corporate treatment gives the owner's SSN or EIN, not the LLC's own EIN.
What happens if I file a 1099 with a wrong TIN?
The IRS can send you a CP2100 or CP2100A notice listing the mismatches. You then have to send the payee a "B notice" asking for a corrected W-9, and if they don't fix it you must start backup withholding at 24% on future payments. Missing or incorrect TINs can also bring per-form penalties for filing incorrect information returns.
Why does the checker say a number could be an SSN or an EIN?
Without dashes, a nine-digit number can be either. SSNs are written XXX-XX-XXXX and EINs XX-XXXXXXX, so if you enter the dashes, or pick the type from the list, the checker can test the right rules.
A spreadsheet turned my TIN into 8 digits. What happened?
Spreadsheets treat TINs as numbers and drop leading zeros, so 012-34-5678 becomes 12345678. Format the column as Text before typing or importing, or add the zero back. The checker flags 8-digit entries for this reason.
File with TINs you can trust
EFileForMe checks every form as you save it, runs IRS TIN Matching on request, collects W-9s online, and e-files your 1099s and W-2s with the IRS and SSA.