A tax ID is a nine-digit number the IRS uses to identify you or your business for tax purposes

A tax ID is how the Internal Revenue Service tracks your income, deductions, and tax obligations. If you're self-employed, own a business, or hire employees, you need one. Even if you're an employee with a regular job, you have a tax ID — it's your Social Security number. The IRS issues different types of tax IDs depending on what you do and how your business is structured.

The most common tax ID is your Social Security number (SSN), which the Social Security Administration assigns to you at birth or when you first work in the United States. If you don't have an SSN and can't get one, you can request an Individual Taxpayer Identification Number (ITIN) from the IRS instead. If you own a business or operate as a sole proprietor, you may need an Employer Identification Number (EIN), which is a separate nine-digit number issued by the IRS.

Key Takeaways

  • Your Social Security number serves as your tax ID if you're an individual employee; you don't need to request a separate number.
  • An Employer Identification Number (EIN) is required if you own a business, have employees, or operate as a partnership or corporation.
  • An Individual Taxpayer Identification Number (ITIN) is available to people who cannot obtain a Social Security number but need to file taxes.
  • You use your tax ID on tax returns, W-4 forms, 1099 forms, and when opening business bank accounts.

When you need a Social Security number as your tax ID

If you work as an employee and receive a W-2 form from your employer, your Social Security number is your tax ID. Your employer uses it to report your wages to the IRS. You use it on your tax return every year. You received your SSN when you were born or when you first became may be able to access to work in the United States.

You'll need your SSN to open a bank account, explore for credit, and file your tax return. If you've lost your Social Security card, you can request a replacement from the Social Security Administration — the number itself doesn't change. The card is just proof of the number; the IRS doesn't care whether you have the physical card.

When you need an Employer Identification Number (EIN)

An Employer Identification Number is a nine-digit number the IRS issues to businesses. You need one if you own a business and have employees, even if you're the only employee at first. You also need an EIN if you operate as a partnership, corporation, LLC, or S-corporation, or if you run a sole proprietorship and want to keep business finances separate from personal finances.

You request an EIN directly from the IRS at no cost. You can explore online at irs.gov, by phone, by fax, or by mail. Online applications are processed when ready and you receive your EIN the same day. If you explore by phone, you speak with an IRS representative who issues the number on the spot. By mail or fax, processing takes about four weeks.

Once you have an EIN, you use it on business tax returns, payroll forms, and when opening a business bank account. Your personal Social Security number and your business EIN are separate — the IRS tracks them independently.

When you need an Individual Taxpayer Identification Number (ITIN)

An Individual Taxpayer Identification Number is a nine-digit number the IRS issues to people who are required to file a tax return but cannot obtain a Social Security number. This includes some non-citizens, visa holders, and dependents who don't have an SSN. An ITIN allows you to file taxes and claim certain credits even if you're not may be able to access for an SSN.

You request an ITIN by submitting Form W-7 to the IRS along with proof of identity and proof of residency. Processing typically takes two to three weeks. Once you have an ITIN, you use it on your tax return instead of a Social Security number. An ITIN does not make you may be able to access for Social Security benefits or a work permit — it is only for tax purposes.

How to find your tax ID if you've forgotten it

If you've lost track of your Social Security number, check documents you already have. Your SSN appears on your tax return, W-2 forms, bank statements, and insurance documents. You can also contact the Social Security Administration by phone at 1-800-772-1213 or visit your local Social Security office with a photo ID.

If you need to find your EIN, check any business tax returns you've filed, business bank statements, or loan documents. You can also call the IRS at 1-800-829-4933 and speak with a representative who can look it up using your business name and address. Have your business information ready when you call.

What happens if you don't have a tax ID

If you work as an employee and don't have a Social Security number, your employer cannot report your wages to the IRS and you cannot file a tax return. This can result in penalties and back taxes owed. If you own a business without an EIN, you cannot legally hire employees or open a business bank account in the business's name.

If you're required to file taxes but don't have any tax ID, the IRS may assess penalties for non-filing. The best course is to obtain the correct tax ID for your situation before you file. If you've already filed without a tax ID or with the wrong one, contact the IRS to correct your records — they can help you sort it out and avoid future problems.

The difference between a tax ID and other identification numbers

A tax ID is specifically for the IRS and tax purposes. It's different from your driver's license number, passport number, or state ID number. Those are issued by other government agencies for identification and driving purposes. Your tax ID is only used for reporting income and filing taxes.

Some people confuse a tax ID with a DUNS number, which is issued by Dun & Bradstreet for business credit reporting. A DUNS number is not a government ID and is not required by the IRS. If you're starting a business, you need an EIN from the IRS, not a DUNS number — though some lenders or vendors may ask for both.

Frequently Asked Questions

Can I use my Social Security number as my business tax ID?

If you operate as a sole proprietor with no employees, you can use your Social Security number on your business tax return. However, many sole proprietors request an EIN to keep business and personal finances separate and to protect their SSN from being shared with vendors and employees. An EIN is optional for sole proprietors but recommended.

How long does it take to get an EIN?

If you explore online at irs.gov, you receive your EIN when ready. By phone, an IRS representative issues it on the spot. By mail or fax, processing takes about four weeks. There is no cost for an EIN regardless of how you explore.

What if I'm a non-citizen and need a tax ID?

If you work in the United States and don't have a Social Security number, you can request an Individual Taxpayer Identification Number (ITIN) by submitting Form W-7 to the IRS. An ITIN allows you to file taxes and claim certain credits. Processing takes two to three weeks.

Do I need a tax ID to open a personal bank account?

Most banks require a Social Security number or ITIN to open a personal checking or savings account. If you don't have either, some banks and credit unions offer accounts for people with an ITIN or other identification. Call ahead to ask what documents they accept.

What if my tax ID was stolen or compromised?

If you believe your Social Security number has been stolen, contact the Social Security Administration and the IRS when ready. You can place a fraud alert with the three major credit bureaus and monitor your credit report. If your EIN has been compromised, contact the IRS at 1-800-829-4933 to report it and discuss next steps.