SS-4

Application for Employer Identification Number

Agency
IRS
Revision
Rev. December 2025
Fillable fields
89
Pages
2
Official source
IRS form page
Checked
October 14, 2026
Fill SS-4 online
Page 1 of form SS-4

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

Form SS-4 is the IRS application for an employer identification number, or EIN. An EIN is a nine-digit number the IRS assigns to sole proprietors, corporations, partnerships, estates, trusts and other entities so they can file returns and report taxes.

You usually need one when you start a business with employees, form a corporation or partnership, open a trust or estate, or take a step that changes your entity type. The IRS says to use only one method per entity, because applying twice can produce two EINs.

After the IRS assigns the number, it mails an EIN notice to the address on the form. If you apply online, you can use the EIN right away and print the notice at the end of the session. You can also fill out Form SS-4 on this page, in your browser, without an account.

Page 1 of Form SS-4 with the title area, lines 1 to 6 and the EIN application layout, sample values

What's on Form SS-4

Lines 1 to 6: who and where

Legal name, trade name, care-of name, mailing address, physical address and the county and state where the business is located.

Lines 7a and 7b: responsible party

The individual who controls the entity, with a Social Security number, ITIN or EIN. It must be a person unless the applicant is a government entity.

Lines 8a to 8c: LLC details

Whether the applicant is an LLC, how many members it has, and whether it was organized in the United States.

Lines 9a to 11: type and reason

The type of entity, the single reason for applying, and the date the business started or was acquired.

Lines 12 to 15: accounting year and employees

The closing month of the accounting year, the highest number of employees expected in the next 12 months, if you want to file Form 944, and the date wages were first paid.

Lines 16 to 18: business activity

The principal activity box, a written description of the line of business, and whether the applicant was issued an EIN before. A signature and optional third-party designee section follow.

How to fill out Form SS-4

  1. 1

    Line 1: legal name

    Enter the name exactly as it appears on the governing document. Individuals use first name, middle initial and last name, with no nicknames. Corporations include a suffix such as Inc. or Corp.

    Line 1 of Form SS-4 with a business's legal name typed exactly as on its governing document, sample values
  2. 2

    Line 2: trade name

    Enter a doing-business-as name only if it differs from the legal name, and use it the same way on later returns.

    Line 2 of Form SS-4 with a trade name entered only where it differs from the legal name
  3. 3

    Lines 4a to 6: addresses

    Give a mailing address on line 4a. Add a physical street address on line 5a only if it differs, and do not use a P.O. box there. Line 6 asks for the county and state of the principal location.

    Lines 4a to 6 of Form SS-4 with a mailing address, a separate street address and the county and state
  4. 4

    Lines 7a and 7b: responsible party

    Name a person, with an SSN, ITIN or EIN on line 7b. If that person has no SSN or ITIN and cannot get one, the instructions say to enter foreign or N/A.

    Lines 7a and 7b of Form SS-4 with a responsible party's name and the taxpayer number, sample values
  5. 5

    Line 9a and line 10

    Check one entity type, and use Other with a description when none fits. On line 10, check only one reason for applying. A box is required.

    Line 9a and line 10 of Form SS-4 with one entity type box and one reason for applying checked
  6. 6

    Line 11 and line 12

    Enter the start or acquisition date. Trusts use the funding date, and estates use the date of death or the date the estate was funded. Then enter the closing month of the accounting year.

    Lines 11 and 12 of Form SS-4 with the business start date and a closing month entered
  7. 7

    Lines 13 to 15: employees

    Enter the highest number of employees expected in the next 12 months, using zero if none. Check the line 14 box to file Form 944 only if you expect employment tax of $1,000 or less. Enter the first wage date on line 15, or N/A.

    Lines 13 to 15 of Form SS-4 with the employee count, the Form 944 box and the first wage payment date
  8. 8

    Lines 16 and 17

    Check one principal activity box, then describe the work in more detail, for example general contractor for residential buildings.

    Lines 16 and 17 of Form SS-4 with a principal activity box checked and a short description of the work
  9. 9

    Third-party designee and signature

    The designee section is optional. Sign as the individual, a principal officer for a corporation, a responsible member or officer for a partnership, or the fiduciary for a trust or estate.

    The third-party designee and signature area at the bottom of Form SS-4 with a principal officer signing

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How and where to apply, and what to expect

Online

The IRS offers an online application at IRS.gov/EIN for applicants whose legal residence, principal place of business or principal office is in the United States or its territories. The EIN can be used immediately.

Fax

Faxing is generally a four business day process. Include your own fax number so the IRS can send the EIN back. The instructions list separate fax numbers for entities in the 50 states and D.C. and for others, and say they may change.

Mail

Apply at least four to five weeks before you need the number. Mail to Internal Revenue Service, Attn: EIN Operation, Cincinnati, OH 45999 for entities in the states or D.C. Other applicants use the EIN International Operation line at the same city and ZIP.

Telephone

Phone applications are for international applicants only, at 267-941-1099, which is not toll-free. The instructions state that the IRS no longer issues EINs by phone to domestic taxpayers.

One per day

The IRS issues one EIN per responsible party per day, across all application methods.

If your EIN has not arrived

When a return is due before the EIN arrives, write Applied For and the application date in the EIN space. Do not use your SSN in its place. To check a status or verify a number, call 800-829-4933.

Changes later

Use Form 8822-B to report a change of responsible party, address or location. The instructions say a responsible party change must be reported within 60 days.

Related forms

Who needs to fill out Form SS-4?

  • A sole proprietor

    A sole proprietor files one Form SS-4 and needs one EIN, even with several businesses or trade names. A new EIN is required if the sole proprietorship incorporates or enters a partnership.

  • A corporation or partnership

    Each corporation, including each member of an affiliated group, needs its own EIN. A partnership applies under its own name.

  • Estates and trusts

    Estates and most trusts apply for an EIN. Certain grantor-type trusts do not need one if the trustee gives payers the grantor's taxpayer number and the trust's address.

  • An LLC

    An LLC answers the LLC questions on lines 8a to 8c. The instructions say a single-member LLC is disregarded by default and a multi-member LLC is a partnership by default.

  • Not for personal use

    The EIN is for business use only. It should not replace a Social Security number or an ITIN.

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Questions about Form SS-4

Can I apply for more than one EIN at once?

No. The IRS issues one EIN per responsible party per day across all methods, and says to use only one application method per entity so you do not receive two numbers.

Can I apply for an EIN by phone?

Only if you are an international applicant, using 267-941-1099. The instructions say the IRS no longer issues EINs by phone to domestic taxpayers.

Can I use the EIN right away?

If you apply online, yes. By fax it generally takes about four business days, and by mail about four weeks.

Who goes on line 7a?

The responsible party. It must be an individual unless the applicant is a government entity, and line 7b takes that person's SSN, ITIN or EIN.

What if I already have an EIN and my entity type changes?

The instructions say an entity that has an EIN keeps it even if its federal tax classification changes under the entity classification rules. A sole proprietorship that incorporates or enters a partnership needs a new one.

Why does the IRS ask for my reason on line 10?

Line 10 requires exactly one reason, such as starting a new business or hiring employees. Pick the one that best matches why you are applying now.