Form SS-4 is the IRS form used to apply for an Employer Identification Number (EIN). Its full name is "Application for Employer Identification Number". Businesses, trusts, estates, non-profits and other entities file it once, the IRS assigns a nine-digit EIN, and that number stays with the entity for good. The form is free to file.
Who Files Form SS-4
Any entity that needs an EIN and does not have one yet: an LLC or corporation after it is formed with the state, a partnership, a sole proprietor who hires employees, a trust, an estate, or a foreign entity with a U.S. filing requirement. If the entity already has an EIN, it does not file again when its name or address changes; see when you need a new EIN.
What Form SS-4 Asks For
| Lines | What you enter |
|---|---|
| 1 to 3 | The legal name of the entity exactly as registered, its trade name if it has one, and a "care of" name |
| 4 to 6 | The mailing address, the street address and the county and state of the principal place of business |
| 7a and 7b | The responsible party: the individual who owns or controls the entity, and their SSN or ITIN if they have one |
| 8a to 8c | Whether the entity is an LLC, how many members it has and whether it was organized in the U.S. |
| 9a and 9b | The type of entity, and the state or foreign country where it was incorporated |
| 10 | The reason for applying, for example "started new business" or "banking purpose" |
| 11 and 12 | The date the business started or was acquired, and the closing month of its accounting year |
| 13 to 15 | The number of employees expected in the next 12 months and the first date wages will be paid |
| 16 and 17 | The principal activity of the business and what it sells |
| 18 | Whether the entity has ever applied for an EIN before |
The form ends with a Third Party Designee section. Filling it in lets someone else, such as a filing service, receive the EIN from the IRS and answer questions about the form on your behalf.
How to Submit Form SS-4
- Online: the IRS online tool asks the same questions and issues the EIN immediately. It is open to entities whose principal place of business is in the U.S. and whose responsible party has an SSN or ITIN.
- Fax: 855-641-6935 for applicants in the 50 states; about 4 business days.
- Phone: international applicants only, 267-941-1099 (not toll-free).
- Mail: Internal Revenue Service, Attn: EIN Operation, Cincinnati, OH 45999; about 4 weeks.
Other fax numbers and the address for applicants outside the U.S. are in where to send an EIN application.
After You File
The IRS confirms the number with Notice CP575, mailed once to the address on the form. If the IRS cannot process the form online it shows a reference number; see EIN reference numbers 101 and 115.
Common Mistakes
- A legal name that does not match the state formation documents
- Naming a company, not an individual, as the responsible party
- Applying before the LLC or corporation legally exists
- Applying a second time for an entity that already has an EIN
If you would like the form prepared and filed for you, see our EIN application service.
Source: IRS, About Form SS-4; IRS, Get an employer identification number. Checked October 2026.
