SSN
Social Security Number
Issued by SSA. Written AAA-GG-SSSS. Reserved patterns never appear: area 000 or 666, group 00, serial 0000.
SSN, ITIN, ATIN, and EIN at a glance
Format can tell them apart. It cannot confirm that any of them was issued.
| Identifier | Issuer | Pattern | Job |
|---|---|---|---|
| SSN | SSA | AAA-GG-SSSS | Wages and benefits |
| ITIN | IRS | 9XX with published groups | Tax filing without an SSN |
| ATIN | IRS | 9XX-93-SSSS | Adoption taxpayer ID, not an ITIN |
| EIN | IRS | XX-XXXXXXX | Business or other entity |
ITIN
Individual Taxpayer ID
Issued by the IRS when someone must file U.S. taxes and is not eligible for an SSN. Area 900–999. Groups 50–65, 70–88, 90–92, and 94–99.
ATIN
Adoption Taxpayer ID
Issued by the IRS for a pending adoption when the child does not yet have an SSN. Area 900–999, group 93. It is not an ITIN.
EIN
Employer Identification Number
Issued by the IRS to businesses and some trusts or estates. Written XX-XXXXXXX. It is not a person’s Social Security Number.
When 9xx is neither an SSN nor a clear ITIN
Areas 900–999 are never Social Security Numbers. Many valid ITINs use specific middle groups published by the IRS, and group 93 is the ATIN pattern. If the first digit is 9 but the middle group falls outside those published ranges, you may have a typo, a foreign identifier pasted into the wrong field, or data that needs review at the source.
The EIN field checks for nine digits in XX-XXXXXXX shape. It does not validate every historical IRS campus prefix or tell you whether the entity is active. Use it to separate a business EIN from a person’s nine-digit tax ID on intake forms.
What each number is for
Work, benefits, and whether you can hold more than one of these numbers.
| Identifier | What it is for | What it is not |
|---|---|---|
| SSN | Work, wages, and Social Security benefits when SSA assigned it | Not a public identity card. Passing the format check does not mean SSA issued the number. |
| ITIN | Federal tax processing when the person is not eligible for an SSN | Does not authorize work, change immigration status, or pay Social Security benefits |
| ATIN | Pending adoption tax return when the child does not yet have an SSN | Not an ITIN and not work authorization |
| EIN | Business, estate, trust, or other entity tax accounts | Not a person’s SSN. Do not use it in place of an SSN or ITIN on a personal return |
SSN vs ITIN
SSA issues the SSN. The IRS issues the ITIN only for federal tax processing when the person is not eligible for an SSN. You cannot keep both. After an SSN is issued, stop using the ITIN and ask the IRS to combine the records.
SSN vs EIN
An EIN identifies a business or other entity. A sole proprietor may file some income-tax returns with a personal SSN or ITIN. An EIN is generally required to hire employees, file employment or excise returns, or run a partnership or corporation. Banks often want one. Apply free at the IRS, not a paid reseller. See Get an EIN.
ITIN vs EIN
An ITIN is a person who cannot get an SSN. An EIN is an entity. Foreign businesses that need a U.S. tax ID use an EIN, not an ITIN.
How to tell them on a form
SSN and ITIN print as AAA-GG-SSSS. An EIN prints as XX-XXXXXXX. If the first digit is 9 and the group is a published ITIN group, treat it as tax-ID territory, not an SSN. The classifier above applies those rules on this device.
Which box on a payroll or vendor form
Employee wages and most individual tax IDs use AAA-GG-SSSS on the W-2 and many onboarding forms. A business paying contractors usually asks for an EIN in XX-XXXXXXX form on a W-9. If someone gives you 9xx in the SSN box, treat it as tax-ID territory and confirm with your policy team. An ITIN is not work authorization and not a substitute for an SSN on Form I-9. This site classifies format only.
How to apply (official pages only)
This site does not file SS-5, W-7, W-7A, or SS-4, and it does not sell “expedited” numbers.
- SSN: Apply at ssa.gov
- ITIN: IRS ITIN (Form W-7)
- ATIN: IRS ATIN (Form W-7A)
- EIN: IRS Get an EIN (Form SS-4)
We do not confirm that a number was issued, run SSNVS, or complete Form I-9. Impossible patterns and 9xx folklore are in the impossible-patterns guide.
Reviewed 21 September 2026 against current SSA and IRS publications.
Frequently Asked Questions
Can an SSN start with 9?
No. SSA does not assign area numbers 900–999 as Social Security Numbers. A 9xx number with a published IRS group is an ITIN pattern; group 93 is an ATIN. Not every 9xx number is an ITIN.
What is the difference between an SSN and an ITIN?
SSA issues the SSN for earnings and benefits. The IRS issues the ITIN only for federal tax processing when the person is not eligible for an SSN. An ITIN does not authorize work or pay Social Security benefits.
Can I have both an ITIN and an SSN?
Not as two active numbers. After an SSN is issued, stop using the ITIN and ask the IRS to combine the tax records.
Can I work with an ITIN?
No. An ITIN is not work authorization and is not a substitute SSN on Form I-9 or payroll.
How do I tell an EIN from an SSN?
An EIN is written XX-XXXXXXX (two digits, a hyphen, then seven). An SSN or ITIN is AAA-GG-SSSS. An EIN identifies a business or other entity, not a person.
Does a sole proprietor need an EIN?
Not always for income tax. The owner’s SSN or ITIN may be enough. An EIN is generally required to hire employees, file employment or excise returns, or run a partnership or corporation. Apply free at the IRS, not a paid reseller.
Is every number starting with 9 an ITIN?
No. ITINs use published middle groups 50–65, 70–88, 90–92, and 94–99. Group 93 is an ATIN. Format is a tell, not an IRS confirmation.
Can the checker confirm a number was issued?
No. It only applies published format rules in your browser. We do not look up people or businesses with SSA or the IRS.