Form SS-4 — Application for Employer Identification Number (EIN)

What is Form SS-4?

Form SS-4, Application for Employer Identification Number, is how you ask the Internal Revenue Service (IRS) for an EIN. An EIN is the 9-digit number (for example 12-3456789) the IRS gives sole proprietors, corporations, partnerships, LLCs, estates, trusts and other entities for tax filing and reporting. The information on the form sets up the entity's business tax account.

The IRS recommends applying online when you can, and the online application is free, but it is only for applicants with a legal residence, principal place of business or principal office in the United States or a U.S. territory. Everyone else applies with Form SS-4 by fax or by mail, or by phone for international applicants, and any applicant may choose the paper form. The current edition is Rev. December 2025.

FileIt takes you through the SS-4 line by line in plain language and prints your answers into the IRS's own PDF, including names with accents or letters such as ł, ś or ș. It keeps the finished form in your vault and can send it for e-signature. You then fax or mail the signed form to the IRS yourself.

Who needs to fill out Form SS-4?

• Founders of a new corporation, partnership or multi-member LLC, including those formed by owners who live outside the United States.
• A foreign-owned single-member U.S. LLC that needs an EIN to file Form 5472.
• Sole proprietors who hire employees, have a qualified plan, or must file excise, employment, alcohol, tobacco or firearms returns.
• Household employers who pay a nanny, caregiver or other household employee.
• Trustees of trusts and executors of estates, which need their own EIN.
• Nonprofits, churches, investment clubs and other organizations opening a bank account or seeking tax-exempt status.
• Anyone who can't or doesn't want to use the IRS online EIN application.

When to use Form SS-4

• When you start a new business or form an entity that needs to show an EIN on a return, statement or other document.
• When you hire your first employees and don't have an EIN yet.
• When you change the type of organization, for example incorporating a sole proprietorship, or buy an existing business.
• When you create a trust or pension plan, or open an estate after a death.
• When you need an EIN only for banking purposes.
• Page 2 of the form, "Do I Need an EIN?", lists which lines to complete for each situation.

What you need before you start

• The entity's exact legal name, and any trade (DBA) name.
• The mailing address, and the physical street address if different. Foreign addresses need the city, province or state, postal code and the country's full name.
• The county and state (or region and country) where the principal business is located.
• The responsible party's name and SSN or ITIN. If they don't have and can't get one, the form takes "Foreign" or N/A.
• The entity type, and for an LLC the number of members and whether it was organized in the United States.
• The reason for applying, the start or acquisition date, and the closing month of the accounting year.
• The highest number of employees you expect in the next 12 months, and when wages will first be paid.
• The principal business activity, plus a short description of what you sell or do.
• A phone number, and a fax number if you want the EIN faxed back.

What’s on Form SS-4

The 2025 edition has 2 pages. FileIt asks for it in 10 parts, and it is signed by Applicant (the entity or individual):

1. Lines 1-3: Who the EIN is forApplicant (the entity or individual)
2. Lines 4-6: AddressesApplicant (the entity or individual)
3. Line 7: Responsible partyApplicant (the entity or individual)
4. Line 8: Limited liability company (LLC)Applicant (the entity or individual)
5. Line 9: Type of entityApplicant (the entity or individual)
6. Line 10: Reason for applyingApplicant (the entity or individual)
7. Lines 11-15: Dates, accounting year and employeesApplicant (the entity or individual)
8. Lines 16-18: Business activity and earlier EINApplicant (the entity or individual)
9. Third party designee (optional)Third-party designee
10. SignatureApplicant (the entity or individual)

How to fill out Form SS-4, step by step

1 Lines 1-3: Names

Line 1 is the legal name exactly as on the charter, partnership agreement, trust instrument or social security card. A sole proprietor enters their own name here and the business name on line 2. Line 2 is the trade or "doing business as" name. Line 3 is the executor, trustee or "care of" person, if any.

2 Lines 4-6: Addresses and location

Line 4 is where the IRS will mail correspondence. Line 5 is the physical street address, only if different, and it can't be a P.O. box. Line 6 is the county and state where the principal business is located. For foreign addresses, don't abbreviate the country name.

3 Line 7: Responsible party

The responsible party is the individual who ultimately owns or controls the entity, such as a principal officer, general partner, grantor or executor. It must be a person, not a company, unless the applicant is a government entity. Give their SSN or ITIN, or "Foreign" if they don't have and can't get one.

4 Line 8: LLC questions

Answer whether the applicant is an LLC (or a foreign equivalent). If it is, give the number of members and say whether it was organized in the United States.

5 Line 9: Type of entity

Check the one box that fits. A single-member LLC that is disregarded checks "Other" and writes "Disregarded entity", or "Foreign-owned U.S. disregarded entity-Form 5472" if that is why it needs the EIN. A multi-member LLC that accepts the default classification checks "Partnership". A corporation writes the form number it will file, such as 1120 or 1120-S, and line 9b says where it was incorporated.

6 Line 10: Reason for applying

Check exactly one reason, such as started a new business, hired employees, banking purpose, changed type of organization, purchased a going business, or created a trust or pension plan, and add the short detail each asks for.

7 Lines 11-15: Dates and employees

Give the date the business started or was acquired, and the closing month of the accounting year (December for a calendar year). Enter the highest number of agricultural, household and other employees expected in the next 12 months, using 0 where none. Line 14 lets small employers choose to file Form 944 once a year instead of Form 941 each quarter. Line 15 is the first date wages were or will be paid, or N/A if you won't have employees.

8 Lines 16-18: Activity and earlier EIN

Check the principal activity on line 16, then describe the main line of business more specifically on line 17, for example "General contractor for residential buildings". Line 18 asks whether the entity has ever applied for and received an EIN before, and if so, which one.

9 Third party designee and signature

Name a designee only if you want someone else, such as an accountant, to receive the EIN and answer questions about the form. That authority ends once the EIN is assigned. Print the signer's name and title, add phone and fax numbers, then sign and date the form.

Common mistakes to avoid

• Putting a business name on line 1 for a sole proprietor. The owner's own name goes on line 1.
• Naming a company as the responsible party. It must be an individual unless the applicant is a government entity.
• Checking "Sole proprietor" for a single-member LLC. A disregarded LLC checks "Other" and writes "Disregarded entity".
• Checking more than one box on line 9a, line 10 or line 16.
• Giving a P.O. box as the street address on line 5a.
• Checking the Form 944 box on line 14 when you expect no employees.
• Forgetting a fax number when you fax the form, so the IRS can't fax the EIN back.
• Applying more than once for the same entity. The instructions say to use only one method so you don't get two EINs.

After you fill it out

Sign and date the form. By fax, the IRS says you'll generally receive the EIN within 4 business days. By mail, apply at least 4 to 5 weeks before you need the number; the EIN arrives by mail in about 4 weeks. The current fax numbers and mailing addresses are in the IRS instructions for Form SS-4, under "Apply by fax" and "Apply by mail", and they depend on whether you have a location in the 50 states or DC.

International applicants may instead call the IRS with the completed form. Write the EIN you're given in the upper-right corner, then sign, date and keep the copy.

Keep your copy and the IRS's EIN notice. FileIt stores the finished PDF in your vault. Later changes of address or responsible party are reported on Form 8822-B, and a change in responsible party must be reported within 60 days.

Form SS-4: frequently asked questions

Official sources

• Blank form (PDF), published by Internal Revenue Service (IRS): https://www.irs.gov/pub/irs-pdf/fss4.pdf
• Official instructions and guidance: https://www.irs.gov/forms-pubs/about-form-ss-4
• Edition shown on this page: Rev. December 2025 (checked 2026-09-28).

FileIt is not affiliated with or endorsed by Internal Revenue Service (IRS) or any government. This page explains the form in general terms and is not legal, tax or immigration advice. Always read the official instructions, and check that you are using the edition the recipient accepts. Page last reviewed 2026-09-28.

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