Where to find your existing tax ID number

Your tax ID number is already on file with the IRS if you have filed taxes before or had a job. The fastest way to find it is to look at documents you already have at home. Check your most recent tax return, W-2 form from your employer, or 1099 form if you are self-employed — your tax ID number (also called an EIN or SSN depending on your business structure) appears on all of these.

If you cannot find those documents, contact your employer's payroll department or the bank or investment company that sent you a 1099. They have your tax ID on record and can confirm it over the phone. You do not need to contact the IRS directly for this — the organization that issued the document can tell you what number they have for you in seconds.

If you are self-employed and cannot locate your EIN, the IRS maintains a searchout tool at irs.gov where you can search by business name and the state where you registered. You will need to know the approximate year you received the EIN.

Key Takeaways

  • Your tax ID number appears on your most recent tax return, W-2, or 1099 form — start by checking those documents first.
  • Your employer, bank, or investment company can confirm your tax ID number by phone if you cannot find it in writing.
  • If you are self-employed and lost your EIN, the IRS EIN lookup tool at irs.gov lets you search by business name and state.
  • A new tax ID is only necessary if you have never worked, never filed taxes, and are starting a business or nonprofit for the first time.

When you need a new tax ID number

You need a new tax ID number only if you have never had one before. This happens when you start a business, form a partnership, create a nonprofit organization, or become self-employed for the first time. If you have worked as an employee, your Social Security number serves as your tax ID — you do not get a new one.

If you are starting a business and need an Employer Identification Number (EIN), you can obtain one free from the IRS. The process takes about 15 minutes online, and you receive your number when ready. You do not need to wait for mail or pay any fee.

How to get an EIN if you are starting a business

Go to irs.gov and search for "explore for an EIN." The IRS offers an online process that takes you through a series of questions about your business structure, location, and the type of work you do. You will need your Social Security number, the date you expect to start business, and the address where your business will operate.

After you submit the form online, the IRS issues your EIN when ready on screen. Write it down or print the confirmation page — you will need this number to open a business bank account, hire employees, or file business taxes. The IRS also emails a confirmation to the address you provide, though the number you receive on screen is valid right away.

If you prefer not to explore online, you can call the IRS Business and Specialty Tax Line at 1-800-829-4933 and request an EIN by phone. A representative will ask the same questions and issue your number during the call. Mail-in applications are also available but take several weeks.

What information you need to locate or obtain a tax ID

To find an existing tax ID, you need only the documents where it appears — your tax return, W-2, or 1099. If you are calling an employer or bank, have your name and date of birth ready so they can verify your identity.

To obtain a new EIN online, gather your Social Security number, the legal name of your business, your business address, and the date you plan to start operations. If you are forming a corporation or LLC, have your state registration number ready — most states issue this when you file your business formation documents.

If you are explore by phone, the IRS representative will walk you through what they need. Have a pen and paper ready to write down your new EIN before you hang up.

Understanding the difference between SSN and EIN

If you work as an employee, your Social Security number (SSN) is your tax ID. Your employer uses it to report your wages to the IRS on your W-2. You do not receive a separate tax ID number for being an employee.

If you are self-employed or own a business, you may have an Employer Identification Number (EIN) in addition to your SSN. An EIN is a nine-digit number that identifies your business to the IRS, separate from your personal tax ID. Sole proprietors can choose to use either their SSN or an EIN for their business, though an EIN keeps your personal and business finances more clearly separated.

Partnerships, corporations, nonprofits, and LLCs must have an EIN — they cannot use a personal Social Security number. If you are unsure which type of tax ID you need, the IRS website has a business structure guide that explains the difference.

What to do if you lost your tax ID number and cannot find it

Start by contacting the last employer or financial institution that issued you a form with your tax ID. They have your number in their system and can provide it by phone or email within one business day.

If you filed taxes in the past three years, you can also contact the IRS directly at 1-800-829-1040 (the main IRS line). Have your name, date of birth, and address ready. The IRS can confirm your tax ID number over the phone, though wait times are often long during tax season.

If you are self-employed and lost your EIN, use the IRS EIN lookup tool at irs.gov. Search by your business name and the state where you registered. If you cannot remember your business name as it was registered, try searching with variations or contact your state's business registration office — they have a record of every business name you registered under.

Protecting your tax ID number

Your tax ID number is sensitive information. Treat it like you would your Social Security number — do not share it in emails, texts, or over the phone unless you initiated the contact and you are certain who you are speaking with.

Scammers sometimes call claiming to be from the IRS and ask for your tax ID or Social Security number. The IRS does not initiate contact by phone about taxes you owe — they send a letter first. If someone calls claiming to be from the IRS and you did not expect the call, hang up and call the IRS directly at 1-800-829-1040 to verify.

Frequently Asked Questions

Is my Social Security number the same as my tax ID number?

If you work as an employee, yes — your Social Security number is your tax ID. If you own a business or are self-employed, you may have a separate EIN, but your SSN is still your personal tax ID. You do not have multiple tax IDs unless you own multiple businesses.

Can I get a tax ID number without a Social Security number?

No. You need a Social Security number or an Individual Taxpayer Identification Number (ITIN) to obtain an EIN. If you do not have a Social Security number, you can explore for an ITIN through the IRS, though the process takes longer and requires additional documentation.

How long does it take to get an EIN?

Online applications are processed when ready — you receive your EIN on screen within minutes. Phone applications also issue the number during the call. Mail-in applications take two to four weeks. There is no reason to use mail unless you cannot access the internet or phone.

Do I need an EIN if I am a sole proprietor?

No, but you can choose to have one. Sole proprietors can use their Social Security number as their business tax ID. An EIN is optional but recommended if you want to keep your personal and business finances separate or if you plan to hire employees.

What if the IRS has the wrong tax ID number on file for me?

Contact the IRS at 1-800-829-1040 with your correct information. Have your name, date of birth, and address ready. The IRS can update your file, though it may take several weeks for the change to appear in all their systems. If you filed taxes with the wrong number, you may need to file an amended return.