Where to Find Your EIN or Tax ID

Your business tax ID number is most likely your Employer Identification Number (EIN), a nine-digit code the IRS assigns to identify your business for tax purposes. If you already have an EIN, the fastest way to find it is to check documents you received when you first registered the business — your EIN appears on your IRS approval letter, your business bank account paperwork, and any tax returns you have filed.

If you cannot locate those documents, you can contact the IRS directly at 1-800-829-4933 (Business and Specialty Tax Line) and provide your business name, address, and the name and Social Security number of the business owner. The IRS can confirm your EIN over the phone. You can also search for your EIN online through the IRS website's EIN lookup tool if you have the business name and address on file.

Some businesses do not have an EIN. Sole proprietors without employees sometimes use their Social Security number instead. If you are unsure whether your business needs an EIN or what number to use, the IRS website has a worksheet that walks you through the decision based on your business structure.

Key Takeaways

  • Your EIN is a nine-digit number assigned by the IRS and appears on your approval letter, bank account documents, and past tax returns.
  • You can call the IRS Business and Specialty Tax Line at 1-800-829-4933 to confirm your EIN if you have lost the original paperwork.
  • Sole proprietors without employees may use a Social Security number instead of an EIN, depending on how the business is structured.
  • The IRS website offers a worksheet to help you determine whether your specific business needs an EIN or can use another tax ID.
  • Once you have your EIN, keep it in a safe place — you will need it for bank accounts, payroll, tax filings, and business licenses.

Check Your Original IRS Approval Letter

When you first obtained your EIN, the IRS sent you a letter (Form SS-4 approval) that displays your nine-digit number prominently at the top. This letter is the clearest source. If you filed it away, check folders labeled "business registration," "tax documents," or "IRS correspondence." Many people keep it with their business license or articles of incorporation.

If you have digital copies, search your email for messages from the IRS or your accountant that may have forwarded the approval letter. The IRS also mailed the letter to the address you provided when you applied, so if you have moved, the letter may be in a box of old mail or with documents from your previous location.

Look at Your Business Bank Account and Tax Returns

Your EIN appears on every document your bank issued when you opened a business account. Check your bank statements, account opening paperwork, or the routing and account information page your bank provided. The EIN is usually listed near the account holder name.

If you have filed any business tax returns — federal income tax, payroll tax, or sales tax returns — your EIN is printed on the first page. Pull copies of past returns from your records or contact your accountant or bookkeeper, who will have copies on file. The IRS also keeps a record of returns you have filed under your EIN, so if you cannot find a copy, you can request a transcript through the IRS website or by calling 1-800-829-1040.

Contact the IRS by Phone or Online

The IRS Business and Specialty Tax Line (1-800-829-4933) can look up your EIN if you provide your business name, the address where the business is located, and the name and Social Security number of the owner or responsible party. Have this information ready before you call. Wait times are typically shorter early in the morning or mid-week.

The IRS also offers an online EIN lookup tool on its website. You will need to enter your business name and the state where it is registered. This tool works best if your business name matches exactly what you registered with the IRS — if you have changed your business name since you obtained the EIN, the lookup may not find it, and you will need to call instead.

Understand When You Need an EIN Versus a Social Security Number

Not every business structure requires an EIN. A sole proprietor with no employees can use their Social Security number for tax purposes instead. However, if you have employees, operate as a partnership, form an LLC or corporation, or plan to open a business bank account, you need an EIN.

The IRS website includes a worksheet that asks questions about your business structure, number of employees, and business type to help you determine whether you need an EIN. If you are unsure, it is safer to obtain one — having an EIN does not hurt, and it keeps your personal Social Security number off business documents and tax filings.

Keep Your EIN in a Safe, Accessible Place

Once you have located your EIN, write it down and store it somewhere you can find it quickly. You will need it when you file taxes, set up payroll, open new business accounts, obtain business licenses, or work with accountants and bookkeepers. Many business owners keep a copy in a folder labeled "Tax Documents" or in a digital file on their computer.

If you have multiple businesses, each one has its own EIN. Keep them organized separately so you do not mix up which number belongs to which business when filing taxes or handling payroll. If you have lost track of an EIN for a business you no longer operate, you can still retrieve it from the IRS using the same phone line or online tool.

Frequently Asked Questions

What if I cannot find my EIN and the IRS cannot find it either?

If the IRS has no record of an EIN under your business name and address, your business may never have been assigned one. You can request a new EIN by filling out Form SS-4 on the IRS website or by calling 1-800-829-4933. The process takes a few minutes by phone and you receive your number when ready.

Can I use my Social Security number instead of an EIN?

Yes, if you are a sole proprietor with no employees and do not plan to hire anyone. However, using an EIN is recommended because it separates your personal and business finances and protects your Social Security number from appearing on business documents. If you later hire employees, you will need to obtain an EIN.

Do I need a different tax ID for state taxes?

Your federal EIN works for federal taxes, but some states require a separate state tax ID number for state income tax, sales tax, or payroll tax. Contact your state's department of revenue or taxation to learn what numbers your business needs. Your accountant can also tell you which state IDs explore to your business.

What if my business name has changed since I got my EIN?

Your EIN stays the same even if you change your business name. You do not need a new EIN. However, you should notify the IRS of the name change by filing Form 8822-B so your tax records are updated. You can file this form online through the IRS website or mail it to the IRS address listed on the form.

How long does it take to get an EIN if I do not have one?

If you explore by phone, you receive your EIN when ready. If you explore online through the IRS website, you get your number right away as well. If you mail Form SS-4, processing takes about four weeks. For most businesses, explore by phone or online is the fastest option.