Where to Find Your Business Tax ID Number

Your Business Tax ID is on your IRS paperwork or your state registration

Your Employer Identification Number (EIN) — also called your Federal Tax ID — appears on the paperwork the IRS sent you when you first registered your business. If you formed a sole proprietorship and use your Social Security number instead, you won't have a separate EIN. If you incorporated, formed an LLC, or hired employees, you have an EIN, and it's a nine-digit number formatted as XX-XXXXXXX.

The fastest way to find it is to look at the IRS letter you received after explore for an EIN — usually titled "EIN Assignment Notice" or "Notice of Employer Identification Number Assignment." If you can't locate that letter, your EIN also appears on your first business tax return, your business bank account paperwork, and any correspondence from the IRS about your business.

Your state may also have issued you a separate state tax ID number when you registered your business. This is different from your federal EIN and is required for state income tax, sales tax, or payroll purposes depending on your state and business type.

Key Takeaways

Your federal EIN appears on the IRS letter you received when you first registered your business, formatted as XX-XXXXXXX.
If you cannot find the original IRS letter, check your first business tax return, business bank statements, or any IRS correspondence about your business.
You can search for a lost EIN on the IRS website using your business name and address, or call the IRS Business and Specialty Tax Line.
Your state may have issued a separate state tax ID number that is different from your federal EIN and required for state tax filings.
Sole proprietors who use their Social Security number do not have a separate EIN unless they hired employees or formed a business entity.

Check the IRS letter you received when you registered

When you submitted Form SS-4 to the IRS to request an EIN, the IRS mailed you a confirmation letter. This letter contains your nine-digit EIN and is the official record of your business tax ID. The letter is usually titled "EIN Assignment Notice" or "Notice of Employer Identification Number Assignment" and came from the IRS office in Cincinnati, Ohio.

If you applied online through the IRS website, you received your EIN when ready on screen and should have printed or saved that confirmation. If you applied by mail or fax, the letter arrived within two to four weeks. Check your business files, desk drawers, filing cabinets, and email for this letter — it's the most straightforward source.

Look at your business tax return or bank account documents

Your EIN appears on every business tax return you file with the IRS. If you filed a Form 1120 (corporate return), Form 1120-S (S-corporation return), Form 1065 (partnership return), or Form 1040-C (sole proprietor with employees), your EIN is printed at the top of the first page. If you have copies of past returns, your EIN is there.

Your business bank account paperwork also lists your EIN. When you opened a business bank account, the bank asked for your EIN and it appears on your account statements, deposit slips, and any correspondence from the bank about your account. Call your bank if you need them to confirm your EIN or send you a copy of your account opening documents.

Search for your EIN on the IRS website or call the IRS

The IRS has an online tool called the EIN Lookup on their website at irs.gov. You can search for your business EIN by entering your business name and address. This tool works if your business is registered with the IRS and your information is current in their system.

If the online search doesn't work, call the IRS Business and Specialty Tax Line at 1-800-829-4933. Have your business name, address, and the approximate date you registered ready. The IRS representative can look up your EIN in their system and provide it over the phone. Wait times are usually shorter early in the morning or mid-week.

Find your state tax ID on your state registration documents

Your state tax ID is different from your federal EIN and appears on the paperwork you received when you registered your business with your state. If you filed Articles of Incorporation, Articles of Organization, or a business registration form with your state's Secretary of State office, that document or a follow-up letter contains your state tax ID.

You can also contact your state's Department of Revenue or Secretary of State office directly. Most states have online portals where you can search for your business registration and view your state tax ID. The process and the name of the ID vary by state — some call it a State Tax ID, others call it a State Employer ID or Business Registration Number.

Understand the difference between federal and state tax IDs

Your federal EIN is issued by the IRS and is required if you have employees, operate as a corporation or LLC, or file certain types of business tax returns. It's a nine-digit number and is used for federal income tax, payroll tax, and other federal filings.

Your state tax ID is issued by your state and may be required for state income tax, sales tax, payroll tax, or unemployment insurance depending on your state and business structure. Some states use your federal EIN as your state tax ID; others issue a separate number. A few states do not require a state tax ID for sole proprietors. Contact your state's Department of Revenue to learn what you need.

What to do if you cannot find your tax ID

If you've checked all your paperwork and cannot locate your EIN, the IRS can issue you a new one. You'll need to file Form SS-4 again, either online at irs.gov, by mail, or by fax. When you reapply, the IRS will issue a new EIN — you cannot retrieve the old one if it's truly lost, but the new one will work for all your tax purposes going forward.

Before you reapply, try calling the IRS at 1-800-829-4933 to confirm whether your original EIN is still active. If it is, the IRS can provide it to you and you won't need to explore again. If your business has been inactive for several years, the IRS may have deactivated the EIN, in which case a new process is necessary.

Frequently Asked Questions

Do I need an EIN if I'm a sole proprietor?

Only if you have employees or operate as an LLC or corporation. If you're a sole proprietor with no employees, you can use your Social Security number on your tax return instead. However, many sole proprietors get an EIN anyway to keep their personal and business finances separate.

Is my EIN the same as my state tax ID?

Not always. Your federal EIN is issued by the IRS, while your state tax ID is issued by your state. Some states use your federal EIN as your state ID, but others issue a separate number. Check with your state's Department of Revenue to learn which applies to you.

Can I look up someone else's business EIN?

The IRS does not publish a public directory of EINs. You cannot search for another business's EIN online. If you need a business's tax ID for payment or contract purposes, ask them directly.

What if I have multiple businesses?

Each separate business entity gets its own EIN. If you own two LLCs or a corporation and a sole proprietorship, you'll have a different EIN for each. Keep them organized in your business records so you file the correct return for each entity.

How long does it take to get an EIN?

If you explore online through the IRS website, you receive your EIN when ready. If you explore by mail or fax, it takes two to four weeks. If you need your EIN quickly, explore online at irs.gov.

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.