To find your tax ID number, start with the documents you already have: for individuals, your Social Security Number (SSN) or Individual Taxpayer Identification Number (ITIN) is printed on prior tax returns, W-2s, and 1099s; for businesses, your Employer Identification Number (EIN) appears on the IRS confirmation letter, business tax returns, and bank paperwork. If none of those turn up, the IRS and Social Security Administration can retrieve or reissue the number for you.
Which Number Is Your Tax ID
Federal law requires an identifying number on any return or tax document you file.1Office of the Law Revision Counsel. 26 USC 6109 – Identifying Numbers Which one you use depends on who you are:
- U.S. citizens and eligible residents use their SSN, assigned by the Social Security Administration.2Social Security Administration. Understanding the Benefits
- People with a federal tax filing obligation who aren’t eligible for an SSN use an ITIN issued by the IRS. Immigration status doesn’t affect eligibility; the ITIN exists purely for tax purposes.3Internal Revenue Service. Individual Taxpayer Identification Number (ITIN)
- Businesses, estates, and trusts use an EIN.
All three are nine digits, and all three do the same job: they tie your income, deductions, and payments to you in IRS records. If you’re adopting a child and can’t yet get their SSN, the IRS also issues a temporary Adoption Taxpayer Identification Number so you can claim the child as a dependent while the adoption is pending.4Internal Revenue Service. Adoption Taxpayer Identification Number
Finding an SSN or ITIN on Documents You Already Have
Before calling anyone, check what’s already in your files. Your SSN or ITIN sits in plain view on more paperwork than most people realize.
- Prior tax returns. Your SSN or ITIN is printed near the top of Form 1040, right next to your name and address.
- W-2 wage statements. Employers send W-2s each January, and your Social Security number appears in Box a.5Internal Revenue Service. General Instructions for Forms W-2 and W-3
- 1099 forms. If you do freelance or contract work, Form 1099-NEC includes your taxpayer identification number in the recipient’s TIN box. For security, the copy you receive may show only the last four digits, which is still enough to confirm the number you have on file.6Internal Revenue Service. Form 1099-NEC – Nonemployee Compensation
- Bank interest statements. Form 1099-INT from your bank or credit union also carries your TIN, though it may be truncated.7Internal Revenue Service. Instructions for Forms 1099-INT and 1099-OID
- SSA correspondence. Letters from the Social Security Administration—benefit statements, award notices, annual earnings summaries—typically include your full or partial SSN in the header.
A W-2 or a prior year’s 1040 is usually the fastest route. Most people have at least one within arm’s reach.
Retrieving It Through IRS and SSA Online Accounts
If the paperwork isn’t at hand, two free federal tools can pull up your number.
IRS Online Account
You can create a free individual account at irs.gov. After identity verification through ID.me, you can view W-2s and certain 1099s filed under your name, see your adjusted gross income, and download tax transcripts.8Internal Revenue Service. Online Account for Individuals A tax return transcript from any prior year shows the SSN or ITIN you filed under.
My Social Security
The Social Security Administration’s “my Social Security” account at ssa.gov shows your earnings record and benefit estimates, and in most states it also lets you request a replacement card.9Social Security Administration. How Do I Apply for a Replacement Social Security Number Card Online Your earnings statement carries your number even if you don’t need a new card.
Finding a Lost Business EIN
A misplaced EIN trips up small business owners more often than you’d expect, in part because the IRS sends its confirmation only once and doesn’t automatically mail a duplicate.
- CP 575 notice. When the IRS first assigns your EIN, it mails a CP 575 confirmation letter. The IRS explicitly warns that it won’t generate a duplicate, so if you still have the original you’re done.10Internal Revenue Service. CP 575 G Notice
- Business tax returns. Form 1120 for corporations and Form 1065 for partnerships both list the EIN near the top of the first page.11Internal Revenue Service. Instructions for Form 1120
- Bank documents. Your business bank required the EIN to open the account. Monthly statements, loan agreements, and credit applications for the business usually have it on file.
- State filings. Business license applications and state tax registrations generally record the federal EIN.
For publicly traded companies, anyone can look up the EIN on the SEC’s EDGAR database. Annual 10-K filings show the EIN on the cover page, and the full-text search at sec.gov/edgar/search covers filings back to 2001.12U.S. Securities and Exchange Commission. EDGAR Full Text Search
Requesting a Replacement or Written Confirmation
Social Security Card
If you need a physical replacement card, or just want the SSA to confirm your number, apply online through your “my Social Security” account where available.13Social Security Administration. Replace Social Security Card If the online option isn’t offered in your state or for your situation, visit a local Social Security office with a government-issued photo ID and a document proving identity, such as a birth certificate or passport. Replacement cards usually arrive within 7 to 10 business days.14Social Security Administration. How Long Will It Take to Get a Social Security Card
EIN Confirmation
Call the IRS Business and Specialty Tax Line at 800-829-4933.15Internal Revenue Service. Telephone Assistance Contacts for Business Customers The representative will verify your identity by asking for the business’s legal name, address, and the name of an authorized officer. Once you’re confirmed, you’ll get the EIN verbally on the call. You can also request Letter 147C, the IRS’s official written confirmation of a previously assigned EIN.16Internal Revenue Service. Employer Identification Number
If you actually need a brand-new EIN rather than a lost one, the online application at irs.gov/ein issues the number immediately. The tool runs Monday through Friday, 7:00 a.m. to 10:00 p.m. Eastern. Paper applications by mail can take several weeks.
What to Do If Your ITIN Has Expired
Finding your ITIN isn’t the whole battle. ITINs don’t last forever. If you don’t use yours on a federal tax return for three consecutive years, it expires automatically on December 31 after that third year.17Internal Revenue Service. How to Renew an ITIN An expired ITIN won’t process; a return filed with it gets rejected or delayed.
To renew, submit Form W-7 with the “Renew an existing ITIN” box checked and attach your identification documents. Spouses and dependents renewing so they can be claimed for a tax benefit must attach the federal return they’ll appear on. Processing typically takes 7 to 10 weeks, and the renewed ITIN arrives by mail. You can check status by calling 800-829-1040 after the seventh week.17Internal Revenue Service. How to Renew an ITIN