The difference between an EIN, SSN, and ITIN comes down to who the number is for. A Social Security Number (SSN) identifies U.S. citizens and noncitizens authorized to work. An Individual Taxpayer Identification Number (ITIN) lets people who owe U.S. taxes but can’t get an SSN file a return. An Employer Identification Number (EIN) identifies a business, trust, estate, or nonprofit as a taxpayer separate from any individual behind it. All three are nine digits, all three are free, and federal law requires one of them on every tax return.1Office of the Law Revision Counsel. 26 USC 6109 – Identifying Numbers
Format and Issuer at a Glance
The three numbers are easy to tell apart on paper. An SSN is written XXX-XX-XXXX and comes from the Social Security Administration. An ITIN uses the same XXX-XX-XXXX layout but always starts with 9, and it comes from the IRS.2Internal Revenue Service. Taxpayer Identification Numbers (TIN) An EIN is written XX-XXXXXXX (two digits, dash, seven digits) and also comes from the IRS.3Internal Revenue Service. Get an Employer Identification Number
The Social Security Number
The SSA issues the SSN primarily to U.S. citizens, and to noncitizens whom the Department of Homeland Security has authorized to work.4eCFR. 20 CFR 422.103 – Social Security Numbers It does two jobs at once. It identifies you to the IRS on tax returns, and it tracks your lifetime earnings so the SSA can later calculate retirement, disability, and survivor benefits. That combination is what sets the SSN apart from the other two numbers, which do tax work only.
Your SSN stays with you for life. It was designed for Social Security purposes but has become the default identifier for banking, credit, and most financial paperwork in the U.S.
There is a narrow path to an SSN without work authorization. If a federal law requires an SSN to receive a government benefit, or a state or local law requires one for public assistance, you can apply with a letter from the benefit-granting agency on official letterhead identifying you, explaining the non-work reason, and citing the specific law.5Social Security Administration. Social Security Numbers for Noncitizens Cards issued this way carry the legend “Not Valid for Employment” and cannot be used to work.4eCFR. 20 CFR 422.103 – Social Security Numbers
The Individual Taxpayer Identification Number
The ITIN exists for one situation: you have a U.S. federal tax filing obligation and you can’t get an SSN. That usually means nonresident aliens who earn U.S. income, resident aliens without work authorization, and dependents or spouses claimed on someone else’s return. The IRS issues the ITIN for tax processing only.6Internal Revenue Service. Individual Taxpayer Identification Number (ITIN)
What an ITIN is not is where people get tripped up. It does not authorize you to work in the United States. It does not make you eligible for Social Security benefits or the Earned Income Tax Credit. It does not change your immigration status. And it does not serve as identification outside the federal tax system.6Internal Revenue Service. Individual Taxpayer Identification Number (ITIN)
An ITIN expires if you don’t use it on a federal tax return for three consecutive tax years, with expiration falling on December 31 of that third year.7Internal Revenue Service. How to Renew an ITIN Renewal is by a fresh Form W-7. If your ITIN appears only on information returns others file about you, such as a 1099 from a bank, you don’t need to renew.
The Employer Identification Number
An EIN is the tax ID for a business or other non-individual entity. Corporations, partnerships, nonprofits, trusts, and estates all need one. Sole proprietors can generally use their own SSN, but once you hire employees, set up a retirement plan, or file excise tax returns, an EIN becomes mandatory.8Internal Revenue Service. Instructions for Form SS-4
The EIN keeps the entity’s tax obligations separate from the personal finances of the people behind it. Banks require one before opening a commercial account: federal rules under the Customer Identification Program require banks to collect a taxpayer identification number for every account holder, and for non-individual customers that means an EIN.9Federal Deposit Insurance Corporation. Customer Identification Program (FFIEC BSA/AML Examination Manual)
Even sole proprietors without employees often get an EIN voluntarily. Every W-9 handed to a client, every 1099 that circulates, and every credit application creates another copy of the number on it. Substituting an EIN keeps the SSN off that paperwork. The application is free and takes minutes online.
When an entity’s ownership or legal structure changes, a new EIN is often required. A sole proprietor who incorporates needs a new one; a partnership that dissolves down to a single continuing partner needs a new one; two corporations merging into a new entity need a new one. A name change or address change alone does not trigger a new EIN, and neither does electing S corporation status.10Internal Revenue Service. When to Get a New EIN
Estates that generate more than $600 in annual income need their own EIN, and if the deceased ran a business, that business needs a new EIN going forward.11Internal Revenue Service. Responsibilities of an Estate Administrator Trusts generally each need their own EIN, and a revocable trust that becomes irrevocable (typically at the grantor’s death) triggers a new number.10Internal Revenue Service. When to Get a New EIN
How To Apply
All three numbers are free. Third-party websites that charge to obtain an EIN are not affiliated with the IRS.3Internal Revenue Service. Get an Employer Identification Number
For an SSN, you submit Form SS-5 with original documents (or agency-certified copies) proving age, identity, and citizenship or immigration status. You can apply in person at an SSA field office or by mail.12Social Security Administration. Application for a Social Security Card The card typically arrives 7 to 10 business days after processing, or 2 to 4 weeks for mail-in applications.13Social Security Administration. How Long Will It Take to Get a Social Security Card?
For an ITIN, you mail Form W-7 along with your federal tax return (unless you qualify for an exception) and identity documents to the IRS ITIN Operation in Austin, Texas.14Internal Revenue Service. Instructions for Form W-7 – Application for IRS Individual Taxpayer Identification Number A passport is the only single document that proves both foreign status and identity. To avoid mailing your original passport, you can use an IRS-authorized Certifying Acceptance Agent, who verifies documents in person; agents may charge their own service fees.15Internal Revenue Service. ITIN Acceptance Agents Processing generally runs 7 to 11 weeks, longer during peak filing season.
For an EIN, the fastest route is the IRS online application, which issues the number immediately at the end of the session. The tool runs Monday through Friday from 6 a.m. to 1 a.m. Eastern, Saturdays from 6 a.m. to 9 p.m., and Sundays from 6 p.m. to midnight. Your principal place of business must be in the United States and the responsible party must have an SSN or ITIN to use it.3Internal Revenue Service. Get an Employer Identification Number Otherwise, you file Form SS-4 by fax (typically four business days) or mail (about four to five weeks).8Internal Revenue Service. Instructions for Form SS-4
What Happens if the Number Is Wrong or Missing
If you don’t give a correct TIN to a payer that needs it, such as a bank, a brokerage, or a client issuing a 1099, federal law requires the payer to withhold 24% of your payments as backup withholding. The same rate applies if the IRS tells the payer your TIN is wrong or you’ve underreported interest and dividend income.16Internal Revenue Service. Topic No. 307 – Backup Withholding The 24% is a prepayment of tax, credited on your return, but it ties up cash until then.
Businesses that file information returns with missing or incorrect TINs face their own penalties. For returns due in 2026, the amounts are $60 per return if corrected within 30 days, $130 if corrected by August 1, $340 if not corrected by August 1 or not filed at all, and $680 per return for intentional disregard, with no cap.17Internal Revenue Service. Information Return Penalties The IRS may waive or reduce penalties for reasonable cause.