How to Find or Request Your Tax ID Number

Where to get your Tax ID number depends on what type of ID you need

A Tax ID number is a nine-digit identifier the IRS uses to track your tax account. If you are a sole proprietor or individual filing taxes, you need either a Social Security Number (SSN) or an Employer Identification Number (EIN). If you run a business with employees or operate as a partnership or corporation, you need an EIN. The IRS issues both, but through different processes and from different offices.

Most individual filers already have an SSN from Social Security. If you do not have one and are a U.S. citizen or permanent resident, you request it from the Social Security Administration, not the IRS. If you need an EIN for a business, you request it directly from the IRS — either online, by mail, or by phone. The online method is fastest and gives you a number the same day.

Key Takeaways

Individual filers use their Social Security Number as their Tax ID; you get this from the Social Security Administration, not the IRS.
Business owners and self-employed people with employees need an Employer Identification Number (EIN), which you request from the IRS.
The IRS issues EINs online at irs.gov/ein the same day you explore, or by phone at 1-800-829-4933 during business hours.
If you are not a U.S. citizen or permanent resident, you may need an Individual Taxpayer Identification Number (ITIN) instead of an SSN.
You only need to request a Tax ID once; the IRS keeps your number on file permanently.

Getting a Social Security Number for individual tax filing

If you are a U.S. citizen or permanent resident and do not have a Social Security Number, you request one from the Social Security Administration (SSA), not from the IRS. You can explore in person at your local Social Security office, by mail, or online at ssa.gov if you are explore for the first time as a U.S. citizen.

To explore in person, bring your birth certificate (original or certified copy), proof of citizenship (passport, naturalization certificate, or consular report of birth abroad), and a photo ID if you have one. The SSA will issue your number on the spot or within two weeks by mail. If you explore by mail, send the same documents to your local Social Security office — the address is on the SSA website.

Once you have your Social Security Number, that is your Tax ID for individual tax filing. You do not need to request anything else from the IRS unless you start a business with employees.

Requesting an Employer Identification Number (EIN) from the IRS

An Employer Identification Number (EIN) is a nine-digit number the IRS issues to businesses, partnerships, corporations, nonprofits, and self-employed people who hire employees. You request an EIN directly from the IRS using Form SS-4. The fastest way is online at irs.gov/ein, where you receive your number when ready after you submit the form.

To explore online, you need your Social Security Number or existing EIN, your business name and address, the date you started or will start your business, and the type of business structure (sole proprietor, partnership, S corporation, C corporation, nonprofit, and so on). The online process takes about 15 minutes. You can print your EIN confirmation when ready and use it right away.

If you cannot explore online, you can explore by phone at 1-800-829-4933 Monday through Friday, 7 a.m. to 10 p.m. Eastern time. Have Form SS-4 filled out before you call. You can also mail Form SS-4 to the IRS address for your state — the form itself lists the correct address. Processing by mail takes four to six weeks.

Getting an Individual Taxpayer Identification Number (ITIN)

If you are not a U.S. citizen or permanent resident but you have income in the United States, you may need an Individual Taxpayer Identification Number (ITIN) instead of a Social Security Number. An ITIN is a nine-digit number that starts with 9 and is used only for tax purposes.

You request an ITIN by filing Form W-7 with the IRS. You must include proof of identity and proof of foreign status — typically a passport, national ID card, or birth certificate. You can file Form W-7 by mail or in person at an IRS office or an authorized acceptance agent (a tax professional or community organization the IRS has certified). Processing takes two to four weeks by mail.

Once you have an ITIN, you use it as your Tax ID on your federal tax return. You do not need a Social Security Number if you have an ITIN.

What to do if you have lost or forgotten your Tax ID number

If you have a Social Security Number but cannot remember it, you can look it up on your Social Security card, previous tax returns, W-2 forms, or 1099 forms. If you do not have access to any of those documents, call the Social Security Administration at 1-800-772-1213 Monday through Friday, 7 a.m. to 7 p.m. Eastern time. Have your name, date of birth, and place of birth ready.

If you have an EIN but cannot find it, check your IRS correspondence, your business bank account paperwork, or your previous business tax returns. If you still cannot locate it, call the IRS at 1-800-829-4933 Monday through Friday, 7 a.m. to 10 p.m. Eastern time. Have your Social Security Number, business name, and business address ready. The IRS can look up your EIN and mail you a confirmation letter.

Using your Tax ID number on tax forms and documents

Once you have your Tax ID number, you use it on every tax return you file, every W-4 form you submit to an employer, and every 1099 form you receive as a contractor or business owner. The IRS matches all your income documents to your Tax ID to make sure your return is complete and accurate.

If you change your business structure — for example, you convert from a sole proprietorship to an LLC — you may need a new EIN. If you straightforward change your business name but keep the same structure, you usually keep the same EIN. When in doubt, contact the IRS at 1-800-829-4933 to confirm whether you need a new number.

Frequently Asked Questions

Do I need both a Social Security Number and an EIN?

Only if you are self-employed with employees or operate as a partnership or corporation. If you are a sole proprietor with no employees, you use your Social Security Number as your Tax ID and do not need an EIN. However, many sole proprietors request an EIN anyway to keep their personal and business finances separate.

Can I get an EIN the same day I explore?

Yes, if you explore online at irs.gov/ein. You receive your number when ready after you submit the form and can print your confirmation. By phone, you get your number during the call. By mail, processing takes four to six weeks.

What if I am not a U.S. citizen — can I still get a Tax ID?

Yes. If you are a permanent resident, you can get a Social Security Number or an EIN. If you are not a permanent resident but have U.S. income, you can get an ITIN by filing Form W-7 with the IRS. An ITIN works as your Tax ID for filing returns and reporting income.

How long does a Tax ID number last?

A Social Security Number and an EIN are permanent. Once the IRS or Social Security Administration issues your number, it stays active for your entire life unless you commit fraud or the number is revoked. You never need to renew it or request a new one unless your business structure changes.

What if I applied for an EIN but never received a confirmation?

If you applied online or by phone, you should have received your number when ready. If you applied by mail and it has been more than six weeks, call the IRS at 1-800-829-4933 with your Social Security Number and business name. The IRS can confirm whether your process was processed and reissue your number if needed.

This guide is for general information only and is not medical, financial, legal, or other professional advice. For decisions specific to your situation, consult a qualified professional. See our Editorial Policy.