IRS Form SS-4: Line-by-Line EIN Instructions
Form SS-4 is the IRS application for an Employer Identification Number. The hard part is not the one-page form—it is choosing the correct responsible party, tax classification, reason for applying and submission route. This guide walks through those decisions using the current December 2025 instructions.
What is IRS Form SS-4?
Form SS-4, Application for Employer Identification Number (EIN), supplies the IRS with the information used to establish an entity's federal business tax account and assign its nine-digit EIN. Applying directly with the IRS is free. Eligible U.S./territory applicants can apply online instead of sending the paper form; fax, mail and an international-only telephone route are also available under current IRS rules.
What Form SS-4 Does—and Does Not Do
Form SS-4 requests an EIN, a nine-digit number used for federal tax filing and reporting. It does not form an LLC, determine your state-law entity status, replace an SSN or ITIN, or by itself make a tax election.
Entity first, EIN second. If you are creating a legal entity such as an LLC or corporation, the IRS instructs you to form the entity through the state before applying for its EIN. That reduces name mismatches and duplicate records.
For the broader EIN process, see How to Get an EIN.
Who Needs an EIN?
The EIN requirement depends on the entity and its federal obligations—not simply whether it is called an LLC. Corporations and partnerships generally need EINs. An LLC may need one because it has employees, multiple members, certain excise-tax obligations, a corporate tax election, or other federal filing requirements. A single-member disregarded LLC can have more nuanced rules depending on employment/excise taxes, ownership and the filing involved.
Do not use “I want to keep my SSN private” as a substitute for checking the federal EIN rules. An EIN can also be useful for business operations such as banking, but “useful” and “federally required” are different questions.
SS-4 Filing Route Navigator
This revision replaces the old “fastest route” logic with an eligibility-first model. Speed matters only after the IRS route requirements are satisfied.
Form SS-4 Instructions: Line by Line
Legal name of entity or individual
CriticalUse the exact legal name. For a newly formed LLC or corporation, match the state formation record. Do not casually substitute a DBA or shortened brand name.
Trade name / DBA
Enter the trade name if it differs from the legal name. Do not repeat the legal name merely to fill the line.
Executor, administrator, trustee or “care of” name
Complete this when applicable to the applicant type or correspondence arrangement. Many ordinary LLC applications leave it blank.
Mailing address
Enter the address where IRS correspondence should be sent. Follow the current foreign-address formatting rules when applicable.
Street address
Enter the entity's physical address only if different from the mailing address. Do not enter a P.O. box here.
County and state of principal business
Enter the entity's primary physical location. Do not automatically use the formation state if the business is principally located somewhere else.
Responsible party
High impactEnter the full name and taxpayer ID of the responsible party. Except for government entities, the responsible party must be an individual—not another entity. If that person has no SSN/ITIN and is ineligible to obtain either, current instructions permit “foreign” or “N/A” on Line 7b; an entry is required.
LLC status, members and U.S. organization
If the applicant is an LLC, state that, enter the number of members, and indicate whether it was organized in the United States. These answers help determine which Line 9a instructions apply.
Type of entity / federal tax classification
High impactDo not choose solely from the state-law label “LLC.” A domestic single-member LLC accepting default disregarded treatment generally uses the IRS's “Other” instruction and identifies itself as a disregarded entity; a domestic multi-member LLC accepting default treatment generally follows the partnership instruction. An LLC electing corporate treatment follows the corporate instructions.
State/foreign country of incorporation
This line applies to corporations. Do not confuse it with the reason for applying; the reason belongs on Line 10.
Reason for applying
RequiredSelect the reason that actually applies, such as started new business, hired employees, banking purpose, changed type of organization, or Other. Special situations may require exact explanatory wording.
Date business started or acquired
Use the date required by the SS-4 instructions for your facts. Do not universally assume this equals the state's LLC approval date. For foreign applicants, the instructions address when the business began or was acquired in the United States.
Closing month of accounting year
Enter the closing month for the applicant's accounting year. December is common for calendar-year taxpayers, but do not assume it applies to every entity.
Highest number of employees expected
Enter the expected number in the agricultural, household and other categories for the next 12 months. Enter zero where appropriate.
Employment-tax / Form 944 question
Answer using the current employment-tax threshold and Form 944 instructions. This is not simply a general request to “choose annual filing”; eligibility and IRS filing requirements control.
First date wages or annuities were paid
Complete when applicable under the form instructions. Businesses with no employees should follow the specific SS-4 directions rather than inventing a date.
Principal activity
Select the category that best describes the applicant's principal activity.
Principal line of merchandise, service or activity
Describe the main product sold, service provided, work performed or other principal activity with enough specificity to identify the business.
Prior EIN
Duplicate checkAnswer whether the applicant entity has previously applied for and received an EIN. Do not request a new EIN merely because you misplaced the old number.
Third-party designee
Use this section only if you want to authorize the named person to receive the EIN and answer questions about completing Form SS-4. The authority ends when the EIN is assigned and released to the designee.
Signature and contact information
Use the authorized signer specified for the applicant type. Foreign applicants may use a duly authorized person as allowed by the current instructions.
How to Submit Form SS-4
| Method | Who can use it | Current timing / destination |
|---|---|---|
| Online | Applicant has legal residence, principal place of business, or principal office/agency in U.S. or U.S. territory and the required valid TIN for the online applicant | EIN can be received and used immediately after successful completion |
| Fax — 50 states/DC | Applicant located under domestic SS-4 fax rule | 855-641-6935; generally about 4 business days when a return fax number is provided |
| Fax — no U.S. state location | No legal residence/principal place/principal office or agency in a state/DC | 855-215-1627 from within U.S.; 304-707-9471 from outside U.S. |
| Eligible applicants using paper SS-4 | Approximately 4 weeks; current instructions say complete it at least 4–5 weeks before the EIN is needed | |
| Telephone | International applicants with no legal residence, principal place of business, principal office or agency in U.S. or U.S. territories | 267-941-1099; Monday–Friday, 6:00 a.m.–11:00 p.m. Eastern; not toll-free |
Current Fax and Mail Destinations
| Applicant location | Fax | |
|---|---|---|
| 50 states or District of Columbia | Internal Revenue Service · Attn: EIN Operation · Cincinnati, OH 45999 | 855-641-6935 |
| No legal residence, principal place of business, principal office or agency in any state/DC | Internal Revenue Service · Attn: EIN International Operation · Cincinnati, OH 45999 | 855-215-1627 (within U.S.) · 304-707-9471 (outside U.S.) |
Re-check immediately before filing. The IRS says fax numbers can change without notice, and its current “Where to File Form SS-4” page is the best operational source for destinations.
Form SS-4 Without an SSN or ITIN
A foreign responsible party does not automatically need to obtain an ITIN before the entity can receive an EIN. Current SS-4 instructions say to enter “foreign” or “N/A” on Line 7b if the responsible party does not have and is ineligible to obtain an SSN or ITIN.
That rule does not make the IRS online EIN application available. The online route has its own taxpayer-ID and location requirements. See Apply for an EIN Without an SSN.
After the EIN Is Assigned
Save the EIN assignment notice with the entity's permanent records. Do not submit another SS-4 because a bank, payment platform or tax preparer asks for proof—provide appropriate EIN documentation instead.
Responsible party changes: the IRS instructs entities to use Form 8822-B to report a responsible-party change, and that change must be reported within 60 days.
Common Form SS-4 Mistakes
- Applying before the legal entity is formed.
- Using a nominee or another company as the responsible party when the natural-person rule applies.
- Assuming Line 7b must contain an ITIN for every foreign owner.
- Choosing “LLC” as though it were a complete federal tax classification on Line 9a.
- Putting the reason for applying on the wrong line.
- Using the state approval date automatically for Line 11 without checking the instructions.
- Submitting the same entity through several methods while waiting.
- Using an outdated fax number or address.
- Requesting a new EIN because the original EIN paperwork was lost.
Still Need to Form the LLC?
Northwest Registered Agent
Form SS-4 does not create the LLC. If the entity has not been formed yet, Northwest is one optional paid formation-assistance provider. Form the entity first, then obtain the EIN using the correct IRS route.
See Northwest's current offer →Affiliate disclosure: Enjoys-life may earn a commission if you use this link. The IRS itself does not charge for an EIN.
Primary IRS Sources
This guide is maintained as an educational Form SS-4 resource. The form revision, responsible-party rule, Line 7b treatment, application routes, phone/fax details, mailing destinations and processing guidance were checked against current IRS primary sources on August 17, 2026.