IRS Form SS-4 applies for an Employer Identification Number, the federal tax ID used to identify a business, estate, trust, plan, nonprofit, and certain other entities.
Eligible U.S. applicants can often receive an EIN immediately through the IRS online application. Fax, mail, and international phone procedures remain available in qualifying cases, but an applicant should obtain only one EIN per responsible party per day.
Last reviewed: July 30, 2026. This article is for general educational purposes and does not replace advice from a qualified tax, legal, financial, or student-aid professional.
What Is IRS Form SS-4?
An EIN identifies the entity’s federal tax account. It does not create the entity, grant tax-exempt status, provide a business license, or replace an SSN or ITIN for personal income-tax filing.
The December 2025 instructions emphasize the responsible party: generally the individual who ultimately owns or controls the entity or exercises ultimate effective control. Nominees generally may not apply as the responsible party.
Who Should Use IRS Form SS-4?
- A new entity hiring employees, opening a business bank account, or filing an entity-level federal return.
- A corporation, partnership, multi-member LLC, estate, trust, retirement plan, nonprofit, or other organization needing an EIN.
- A sole proprietor who has employees, a qualified retirement plan, certain excise duties, or another EIN requirement.
- An existing business undergoing an ownership or structural change that requires a new EIN under IRS rules.
- Not every business name or address change; many changes keep the existing EIN.
How to Use or Complete IRS Form SS-4
- Legally form the entity with the state or governing authority before applying when formation is required.
- Determine the true responsible party and obtain the required SSN, ITIN, or EIN.
- Choose the entity type and explain the principal reason for applying.
- Enter legal name, trade name, address, start date, closing month, expected employees, and principal activity.
- Apply online if eligible, or submit the signed form by fax, mail, or international phone under the current instructions.
- Save the EIN confirmation permanently and use the legal name and EIN consistently on returns, payroll filings, bank accounts, and licenses.
EIN Application Methods and Timing
| Method | General result |
|---|---|
| IRS online EIN application | Immediate EIN after successful completion; for eligible U.S. applicants. |
| Fax | Generally about four business days when a return fax number is provided. |
| Generally about four to five weeks. | |
| International phone | Applicants with no U.S. legal residence, principal place of business, or principal office may call 267-941-1099 during posted hours. |
Who Is the Responsible Party?
For most entities, the responsible party is an individual who owns, controls, or exercises ultimate effective control. For certain government entities, trusts, estates, and tax-exempt organizations, the definition is adapted to the person with authority over funds or assets.
A formation service, attorney, employee, or other nominee should not be listed merely for convenience. If the responsible party later changes, report it on Form 8822-B generally within 60 days.
When a Business Needs a New EIN
A new EIN may be required after incorporation of a sole proprietorship, certain ownership changes, formation of a new partnership, bankruptcy-estate creation, or another structural event. A mere name change, address change, or election of S corporation treatment generally does not by itself require a new EIN.
The answer depends on both legal form and tax classification. Check the IRS entity-specific rules before applying, because duplicate EINs create filing and account problems.
Avoid EIN Application Scams
The IRS does not charge for an EIN. Commercial services may charge to prepare or submit the application, but their websites should not be confused with IRS.gov.
Do not submit multiple online applications when a result is uncertain. Save the confirmation page and contact the IRS Business and Specialty Tax Line if an EIN letter is lost or an account must be verified.
Before You File or Submit
- Use the current official version. Tax forms, addresses, thresholds, and electronic filing procedures can change. Download the form or instructions from the issuing agency immediately before use.
- Match names and taxpayer identification numbers. Confirm that legal names, SSNs, ITINs, EINs, plan numbers, and tax periods agree with the related return and agency records.
- Gather supporting records first. Keep calculations, statements, notices, authorizations, appraisals, receipts, and other documents that support every entry.
- Check the deadline and delivery method. An extension to file does not necessarily extend the time to pay. Private carriers also may require a different street address than USPS.
- Sign where required. An unsigned paper form, missing consent, or incomplete electronic authentication can delay or invalidate a submission.
- Keep a complete copy. Retain the filed form, attachments, confirmation number, proof of mailing, fax confirmation, and payment record.
Common Mistakes to Avoid
- Applying before the entity is legally formed.
- Listing a nominee instead of the true responsible party.
- Choosing an entity type based only on a trade name or state label.
- Requesting a new EIN for a simple address or business-name change.
- Submitting multiple applications and creating duplicate accounts.
- Paying a lookalike site while believing the fee is charged by the IRS.
What Happens After Submission?
The EIN assignment notice confirms the number and legal name. Review it immediately and correct errors before filing returns or opening accounts.
An entity with an EIN must file all returns the IRS expects until a final return or account-closure procedure is completed, even if the business never begins operations.
Processing time is not the same as a legal deadline. Do not submit a duplicate merely because an acknowledgement or response has not arrived. First check the relevant online status tool, confirmation record, or official contact channel. If the agency requests more information, respond by the date and method stated in the notice.
Records to Keep
Keep a copy of the completed submission and all documents used to prepare it. Your file should also contain the tax-year or period involved, the date submitted, the delivery method, any confirmation or tracking number, and notes about later agency correspondence. Retention periods depend on the form and issue, so follow the specific instructions and keep records longer when they may remain material to an audit, refund claim, basis calculation, collection case, election, or amended return.
Frequently Asked Questions
How much does an EIN cost?
The IRS application is free. A third-party preparer may charge a separate service fee.
Can I get an EIN without an SSN?
Some applicants can use an ITIN or follow foreign-applicant procedures, but the responsible-party field and online eligibility rules are specific. Review the current instructions.
Can an LLC use its owner’s SSN?
A disregarded single-member LLC may use the owner’s TIN for certain income-tax reporting, but it may still need its own EIN for employment, excise, banking, or other purposes.
Does an EIN expire?
No. An assigned EIN remains associated with that entity and is not reused, although the IRS account may later be closed.
Official Resources
Bottom line: Form the entity first, identify the real responsible party, use the free IRS online tool when eligible, apply only once, and preserve the EIN notice permanently.