A Tax ID Has 9 Digits, Formatted as XX-XXXXXXX

A federal tax ID—also called an Employer Identification Number (EIN)—contains exactly 9 digits. The Internal Revenue Service (IRS) formats it with a hyphen after the first two digits, so it looks like this: 12-3456789. The first two digits identify the state or region where the business was formed or where the principal place of business is located. The remaining seven digits are a unique serial number assigned by the IRS.

If you are a sole proprietor with no employees, you may use your Social Security Number (SSN) as your tax ID instead of getting an EIN. A Social Security Number has 9 digits too, but it is formatted differently: XXX-XX-XXXX. The IRS accepts either one for tax filing purposes, though an EIN keeps your personal and business finances more clearly separated.

Individual taxpayers filing personal income tax returns do not need a separate tax ID—they use their Social Security Number, which serves as their tax identification. Businesses, partnerships, nonprofits, and trusts all need an EIN if they have employees or file certain types of tax returns.

Key Takeaways

  • An EIN has 9 digits formatted as XX-XXXXXXX, with the first two digits representing the state or region where the business operates.
  • The IRS assigns the remaining seven digits as a unique serial number to distinguish one business from another.
  • Sole proprietors can use either an EIN or their Social Security Number as a tax ID, depending on their business structure and filing needs.
  • Social Security Numbers also contain 9 digits but use a different format (XXX-XX-XXXX) and serve as the tax ID for individual filers.
  • Businesses with employees, partnerships, and nonprofits must obtain an EIN rather than using a personal Social Security Number.

What the First Two Digits Tell You

The first two digits of an EIN are not a random pair—they correspond to the state where the business is incorporated or where it maintains its principal office. For example, EINs beginning with 01 through 02 are assigned to businesses in New Hampshire. EINs starting with 03 through 04 go to Maine. The IRS maintains a complete list of these state codes, and you can look up which state a particular EIN belongs to by checking the first two digits.

This does not mean the business must operate only in that state. A company incorporated in Delaware but running operations in California will still have a Delaware-based EIN prefix. The state code straightforward reflects where the business was registered or where it filed its formation documents with the state.

How the Remaining Seven Digits Work

Once the IRS assigns the first two digits based on state, the remaining seven digits are issued sequentially as new businesses request EINs. These seven digits are unique—no two businesses will ever receive the same complete 9-digit EIN. The IRS uses this numbering system to may support every business entity has a distinct identifier in the tax system.

The seven-digit sequence does not encode any additional information about the business itself. Unlike some identification systems that embed details like the business type or the year it was formed, an EIN's final seven digits are straightforward a serial number. If you know only the last seven digits of an EIN, you cannot determine anything about the business—you need the full 9-digit number to look it up in IRS records.

EIN Versus Social Security Number for Tax Purposes

A Social Security Number is 9 digits formatted as XXX-XX-XXXX. It is assigned to individuals at birth or when they first work in the United States. The IRS uses SSNs as the tax ID for personal income tax returns, and they also appear on W-2 forms, 1099 forms, and other tax documents tied to an individual.

An EIN is formatted differently (XX-XXXXXXX) and is issued only to business entities, trusts, estates, and certain organizations. If you are a sole proprietor with no employees, you can file business taxes using your SSN. However, if you hire employees or want to keep your business finances separate from your personal finances, you should obtain an EIN. Many banks and vendors also prefer to see an EIN rather than a personal SSN when dealing with a business.

Where to Find Your Tax ID

If you have an EIN, it appears on the IRS letter you received when you first obtained it. That letter, called a Form SS-4 confirmation, is sent to the address you provided when you requested the EIN. Keep this letter in your business records—you will need the EIN for tax returns, payroll filings, and opening a business bank account.

If you have lost the letter or cannot locate your EIN, you can call the IRS Business and Specialty Tax Line at 1-800-829-4933. Have your business name, address, and the approximate date you received the EIN ready. The IRS can look up your EIN by phone and provide it to you when ready.

For a Social Security Number, you can find it on your Social Security card, tax returns you have already filed, or by contacting the Social Security Administration directly. Your SSN also appears on W-2 forms and other tax documents sent to you by employers or financial institutions.

Common Mistakes When Writing or Reporting a Tax ID

The most frequent error is transposing digits or forgetting the hyphen. An EIN must be written as XX-XXXXXXX with the hyphen in the correct place. Some forms and systems accept EINs without the hyphen (as a 9-digit string), but always double-check before submitting. A single digit out of place can cause the IRS to route your return to the wrong business or reject it entirely.

Another common mistake is confusing an EIN with a state tax ID number. Many states issue their own business identification numbers for state income tax or sales tax purposes. These are separate from the federal EIN and have different formats depending on the state. You may need both a federal EIN and a state tax ID, so verify which one a particular form or agency is asking for.

Do not share your EIN or SSN with anyone who has not provided a legitimate business reason for requesting it. Scammers sometimes pose as IRS agents or vendors and ask for tax IDs over the phone or email. The IRS will never initiate contact by email or text message, and legitimate vendors will explain why they need the number.

Frequently Asked Questions

Can I change my EIN if I do not like the number?

No. The IRS does not reassign EINs, and you cannot request a different one straightforward because you prefer a different number. An EIN is permanent for your business. If you close the business and later start a new one, you will receive a new EIN, but you cannot swap out the original.

Do I need an EIN if I am a sole proprietor with no employees?

You can use your Social Security Number instead. However, getting an EIN is free and keeps your personal and business finances separate, which many accountants recommend. An EIN also makes it easier to hire employees later without having to explore for one at that time.

What if someone uses my tax ID fraudulently?

Contact the IRS when ready at 1-800-829-1040 and report the fraud. The IRS has procedures to flag your account and investigate. Also file a report with the Federal Trade Commission at IdentityTheft.gov. Keep records of any suspicious activity and correspondence with the IRS.

Is an EIN the same as a business license number?

No. An EIN is a federal tax identifier issued by the IRS. A business license number is issued by your city or county and is used for local regulatory purposes. You may need both, and they serve different functions in the tax and regulatory system.

How long does it take to receive an EIN after I explore?

If you explore online through the IRS website, you receive your EIN when ready. If you explore by mail or fax, it typically takes two to four weeks. The online process is the fastest option and is available to most business types.