Form SS-4: How to Apply for an Employer Identification Number

Form SS-4 is the IRS application for an employer identification number, called an EIN. An EIN is a nine-digit number that businesses, trusts, estates, and other entities use for tax purposes. The form says it is for employers, corporations, partnerships, trusts, estates, churches, government agencies, tribal entities, certain individuals, and others.

This post is general information from the form (Rev. December 2025). The form says to read the separate instructions for each line at www.irs.gov/FormSS4. It does not tell you what to do in your case.

Do you need an EIN?

The form says to file Form SS-4 if the entity does not already have an EIN but must show one on a return, statement, or other document. The form includes a table of situations. A few examples:

• You started a new business and expect no employees. Complete the basic lines, including the entity type and the reason for applying.
• You hired employees, including household employees. The table asks you to complete more lines, including the questions about employees.
• You need an EIN only to open a bank account. The table asks for a smaller set of lines.
• You changed the type of organization, for example by incorporating a sole proprietorship or forming a partnership.
• You are a withholding agent for taxes on nonwage income paid to a nonresident alien.
• You are an S corporation and need an EIN to file Form 2553.

Who must have an EIN

A footnote on the form says that a sole proprietor who sets up a qualified retirement plan, or who must file excise, employment, alcohol, tobacco, or firearms returns, must have an EIN. A partnership, corporation, nonprofit organization, or farmers' cooperative must use an EIN for any tax-related purpose, even if it has no employees.

The lines that cause the most trouble

Line 1 is the legal name of the entity or individual. Line 2 is the trade name, if it is different. Line 7a is the name of the responsible party, and line 7b is that person's SSN, ITIN, or EIN.

Line 8a asks whether this is an application for a limited liability company. If you answer yes, line 8b asks for the number of members, and line 8c asks whether the LLC was organized in the United States. The form warns that you should read the instructions for the correct box on line 9a.

Line 9a asks for the type of entity, and you check only one box. A sole proprietor enters an SSN. Line 13 asks for the highest number of employees expected in the next 12 months. Line 14 is a check box for filing Form 944 instead of quarterly Forms 941, if you expect a small employment tax liability. Line 18 asks whether the entity has ever applied for and received an EIN.

Do not apply for a new EIN by mistake

A footnote on the form says that you should not apply for a new EIN if the existing entity only changed its business name. It also says not to apply again if the entity only elected a different tax classification on Form 8832.

A partnership whose status ends because at least 50 percent of its interests were sold or exchanged within a 12-month period should keep using the EIN it had. The form also says not to use the EIN of a prior business unless you became the owner of a corporation by acquiring its stock. A corporation that is electing or revoking S corporation status should use its previously assigned EIN.

The name must match later filings

Form 8809, the extension request for information returns, warns that its legal name and TIN must be exactly the same as the name you gave when you applied for the EIN on Form SS-4. Do not use abbreviations. Check the name before you apply, and keep a copy of what you sent.

Before you sign

• Confirm the legal name, the mailing address, and the responsible party on lines 1, 4a, and 7a.
• Check the entity type on line 9a, and read the LLC questions on lines 8a to 8c if they apply.
• Check whether you already have an EIN, and enter it on line 18 if you do.
• Read the declaration above the signature. It is made under penalties of perjury.
• Keep a copy for your records, as the form instructs.

Related posts

For the S corporation election that needs an EIN, read Form 2553: Electing S Corporation Status. For the entity classification election, read Form 8832: Choosing How Your LLC Is Taxed. For the extension request that must match your EIN name, read Form 8809: Asking for More Time to File Information Returns.

Sources: Sources: IRS, Form SS-4, Application for Employer Identification Number (Rev. December 2025) (https://www.irs.gov/pub/irs-pdf/fss4.pdf) This is general information, not advice about your specific return.

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