All articles 4 min read

Taxpayer Identification Numbers for a Small Business: Small-Business Taxes (2025 IRS Guide)

This guide covers “Taxpayer Identification Numbers for a Small Business” within small-business taxes. The following material presents the IRS treatment of this topic, including the qualifications, exceptions, and examples in the source section. Read the rules alongside the facts of your own situation before deciding what to report, deduct, or document.

Adapted from Publication 334 (2025), Tax Guide for Small Business, published by the Internal Revenue Service. This guide retains the source edition’s years, amounts, deadlines, and examples. It is guidance for that edition, not a statement that the same figures apply to every tax year.

Taxpayer Identification Numbers for a Small Business

This section explains three types of TINs, who needs them, when to use them, and how to get them.

Social security number (SSN).

Generally, use your SSN as your TIN. You must report this number on each of your individual income tax forms, such as Form 1040 and its schedules.

To apply for an SSN, use Form SS-5, Application for a Social Security Card. This form is available at Social Security Administration (SSA) offices or by calling 800-772-1213. It is also available from the SSA website at SSA.gov/forms/ss-5.

Individual taxpayer identification number (ITIN).

The IRS will issue an ITIN if you are a nonresident or resident alien and you do not have and are not eligible to get an SSN. The ITIN will expire for any taxpayer who does not file a federal income tax return (or who is not included as a dependent on the return of another taxpayer) for 3 consecutive years. In general, if you need to obtain an ITIN, you must attach Form W-7, Application for IRS Individual Taxpayer Identification Number, with your signed, original, completed tax return and any other required documentation and mail them to the address in the Instructions for Form W-7. Exceptions are covered in the instructions. If you must include another person’s SSN on your return and that person does not have and cannot get an SSN, enter that person’s ITIN. The application is also available in Spanish. The form is available at IRS.gov/FormW7.

.An ITIN is for tax use only. It does not entitle the holder to social security benefits or change the holder’s employment or immigration status..

Employer identification number (EIN).

You must also have an EIN to use as a TIN if you do either of the following.

  • Pay wages to one or more employees.

  • File pension or excise tax returns.

If you must have an EIN, include it along with your SSN on your Schedule C (Form 1040) as instructed.

You can apply for an EIN:

  • Online by going to IRS.gov/EIN. As long as the principal business location is in the United States or U.S. territories, the EIN is issued immediately once the application information is validated;

  • By telephone at 267-941-1099 (not a toll-free number) only if the principal business is located outside the United States or U.S. territories; or

  • By mailing or faxing Form SS-4, Application for Employer Identification Number.

New EIN.

You may need to get a new EIN if either the form or the ownership of your business changes. For more information, see Pub. 1635, Understanding Your EIN.

When you need identification numbers of other persons.

In operating your business, you will probably make certain payments you must report on information returns. These payments are discussed under Information Returns, later in this chapter. You must give the recipient of these payments (the payee) a statement showing the total amount paid during the year. You must include the payee’s identification number and your identification number on the returns and statements. See the General Instructions for Certain Information Returns.

Employee.

If you have employees, you must get an SSN from each of them. Record the name and SSN of each employee exactly as they are shown on the employee’s social security card. If the employee’s name is not correct as shown on the card, the employee should request a new card from the SSA. This may occur if the employee’s name was changed due to marriage or divorce. See Pub. 15.

Form W-4, Employee’s Withholding Allowance Certificate, is completed by each employee so the correct federal income tax can be withheld from their pay.

If your employee does not have an SSN, they should file Form SS-5 with the SSA.

Other payee.

If you make payments to someone who is not your employee and you must report the payments on an information return, get that person’s SSN. If you must report payments to an organization, such as a corporation or partnership, you must get its EIN.

To get the payee’s SSN or EIN, use Form W-9, Request for Taxpayer Identification Number and Certification.

A payee who does not provide you with an identification number may be subject to backup withholding. For information on backup withholding, see the Instructions for the Requester of Form W-9 and the General Instructions for Certain Information Returns.

Using the guidance

Keep the documents that establish the dates, amounts, and circumstances described above. References to other chapters, forms, worksheets, or earlier and later sections refer to the linked IRS publication. Check the full publication and its updates before relying on a rule for a different tax year or a situation not addressed here.

Sources and further reading

The cited U.S. government text is in the public domain. Source accessed October 28, 2026. Fynoptic has organized this material for educational use and is independent of, and not endorsed by, the IRS.

Back to all articles