IRS Instruction SS-4 – IRS Forms, Instructions, Pubs 2026

IRS Instruction SS-4 – IRS Forms, Instructions, Pubs 2026 – If you’re starting a business, hiring employees, or managing an estate or trust, obtaining an Employer Identification Number (EIN) is often a crucial first step for tax compliance. IRS Form SS-4, officially known as the Application for Employer Identification Number, is the key document for this process. The accompanying instructions, outlined in IRS Instruction SS-4, provide detailed guidance on how to complete the form accurately and efficiently. In this comprehensive guide, we’ll break down everything you need to know about the latest instructions for Form SS-4, including who needs an EIN, application methods, step-by-step filling instructions, recent updates, and tips to avoid common pitfalls. Whether you’re a sole proprietor, corporation owner, or nonprofit administrator, this article will help you navigate the EIN application process seamlessly in 2026.

What Is IRS Form SS-4 and Why Do You Need It?

Form SS-4 is a federal tax form used to apply for an EIN, a unique nine-digit number (formatted as XX-XXXXXXX) assigned by the IRS to identify businesses and other entities for tax purposes. An EIN functions much like a Social Security Number (SSN) for individuals but is specifically for business-related tax filing, reporting, and banking activities. It’s required for opening business bank accounts, filing employment tax returns, and complying with IRS regulations.

The instructions for Form SS-4 explain the form’s purpose in detail: to establish a business tax account with the IRS. Unlike an SSN or Individual Taxpayer Identification Number (ITIN), an EIN is strictly for business use and should not be substituted for personal identification. If your entity already has an EIN, you generally don’t need to apply for a new one unless there’s a significant change, such as converting from a sole proprietorship to a corporation.

Who Must Apply for an EIN Using Form SS-4?

Not every individual or entity needs an EIN, but the instructions specify several scenarios where it’s mandatory. Here’s a breakdown:

  • Business Owners and Employers: Sole proprietors, corporations, partnerships, and LLCs must apply if they hire employees, operate as a corporation or partnership, or file certain tax returns like employment, excise, or alcohol/tobacco/firearms taxes.
  • Sole Proprietors: Even without employees, you need an EIN for banking purposes, pension plans, or filing Schedule C (Form 1040) with a qualified joint venture.
  • Trusts and Estates: Trustees or executors apply for revocable trusts, estates of decedents, or pension plans.
  • Nonprofits and Government Entities: Churches, nonprofits, state/local governments, Indian tribal enterprises, and REMICs (Real Estate Mortgage Investment Conduits) require an EIN for tax-exempt status applications or reporting.
  • Disregarded Entities: Single-member LLCs or foreign-owned U.S. entities filing Form 5472 need an EIN for employment or excise taxes.
  • Other Cases: Withholding agents for nonresident aliens, household employers, or entities created for banking/compliance purposes.

Sole proprietors typically need only one EIN, even for multiple businesses, unless they incorporate or form a partnership. Each corporation in an affiliated group, however, requires its own EIN.

If you’re unsure, the instructions include a “Do I Need an EIN?” section to help determine eligibility.

How to Apply for an EIN: Methods Outlined in the Instructions?

The IRS emphasizes applying online for the fastest results, but other options are available depending on your location and needs. Importantly, use only one method per entity to avoid duplicate EINs, and applications are limited to one per responsible party per day.

Online Application (Recommended)

  • Available at IRS.gov/EIN for applicants with a principal business, office, or legal residence in the U.S. or its territories.
  • Free, instant issuance upon completion (view, print, or save your EIN notice).
  • Requires a valid Taxpayer Identification Number (TIN) for the responsible party (e.g., SSN, ITIN, or EIN).
  • Session times out after 15 minutes of inactivity, so prepare all info in advance.
  • Operating hours: Monday–Friday, 7 a.m. to 10 p.m. ET.

By Phone (International Applicants Only)

  • Call 267-941-1099 (not toll-free) from 6 a.m. to 11 p.m. ET, Monday–Friday.
  • Provide details from a completed Form SS-4; an IRS representative will assign the EIN immediately.
  • Domestic applicants can no longer use this method—a key update from prior years.

By Fax

  • Fax a completed Form SS-4 to:
    • 855-641-6935 (50 states and D.C.).
    • 855-215-1627 (U.S. territories) or 304-707-9471 (international, with charges).
  • Include your return fax number; receive EIN in about 4 business days.
  • Available 24/7.

By Mail

  • Mail to: Internal Revenue Service, Attn: EIN Operation (or EIN International Operation for territories/international), Cincinnati, OH 45999.
  • Allow 4–5 weeks for processing; apply at least that far in advance if needed urgently.

For fax or mail, download the fillable Form SS-4 from IRS.gov. You can authorize a third-party designee (e.g., an accountant) on Line 18 to receive the EIN and handle questions.

Step-by-Step Guide to Completing Form SS-4

The instructions provide line-by-line guidance to ensure accuracy. Enter “N/A” for inapplicable lines, and use black ink if mailing/faxing. Here’s a summary:

  1. Line 1: Legal name of the entity or individual (must match SSN card, charter, or trust document).
  2. Line 2: Trade name or DBA (if different from Line 1).
  3. Line 3: “Care of” name (e.g., executor or trustee).
  4. Lines 4a–4b: Mailing address (include foreign details if applicable).
  5. Lines 5a–5b: Physical address (if different; no P.O. boxes).
  6. Line 6: County and state of principal business.
  7. Lines 7a–7b: Responsible party’s name and TIN (required; report changes via Form 8822-B within 60 days).
  8. Lines 8a–8c: LLC details (yes/no, number of members, U.S.-organized?).
  9. Line 9a: Entity type (e.g., sole proprietor, corporation—specify form number; check “Other” and explain if needed).
  10. Line 9b: State or foreign country of incorporation (for corporations).
  11. Line 10: Reason for applying (e.g., started new business—specify type).
  12. Line 11: Business start/acquisition date.
  13. Line 12: Accounting year closing month.
  14. Line 13: Expected employees in next 12 months (by category).
  15. Line 14: Elect to file Form 944 annually if liability ≤$1,000 (reinstated in 2024; for territories, wages ≤$6,536).
  16. Line 15: First wages paid date (or N/A).
  17. Line 16: Principal activity (check one or specify “Other”).
  18. Line 17: Detailed business description.
  19. Line 18: Prior EIN? (Yes/No; provide if yes).
  20. Third-Party Designee: Optional authorization.
  21. Signature: By authorized person (date and phone/fax).

For visual reference, here’s a sample of Form SS-4:

Recent Updates to Form SS-4 Instructions for 2026

The instructions were revised in December 2025 (Catalog No. 62736F), with no major changes announced specifically for 2026 beyond ongoing adjustments. Key recent developments include:

  • Reinstatement of Line 14 for electing Form 944 (annual filing) if tax liability is low—effective since March 2024.
  • No more phone applications for domestic taxpayers; international only.
  • Updated fax and mail addresses consolidated in Cincinnati, OH.
  • Emphasis on online applications and using Form 8822-B for changes.
  • Absorption of certain publications (e.g., Pub. 51 and 80) into Pub. 15.

For the latest, check IRS.gov/FormSS4, as tax laws can evolve.

Common Mistakes to Avoid When Using Form SS-4

Based on the instructions, here are frequent errors and how to prevent them:

  • Applying multiple times or via multiple methods, leading to duplicates.
  • Using abbreviations, nicknames, or trade names on Line 1 instead of the legal name.
  • Failing to report responsible party changes within 60 days.
  • Incorrect entity classification for LLCs (use Form 8832 if electing differently).
  • Abbreviating country names on foreign addresses.
  • Applying for unnecessary EINs (e.g., grantor trusts often don’t need one).
  • Delaying mail/fax submissions when time-sensitive.

Always double-check details and keep a copy of your application.

FAQs About IRS Instructions for Form SS-4

1. How long does it take to get an EIN?

Online: Immediate. Fax: 4 business days. Mail: 4–5 weeks. Phone (international): Immediate.

2. Can I apply for an EIN without a business yet?

Yes, if anticipating needs like banking or hiring.

3. What if I lose my EIN?

Contact the IRS at 800-829-4933 or check your confirmation notice.

4. Is there a fee for Form SS-4?

No, it’s free.

5. How do I update my EIN information?

Use Form 8822-B for address or responsible party changes.

Final Thoughts on Applying for Your EIN

Navigating IRS Instruction SS-4 doesn’t have to be overwhelming. By following the step-by-step guidance and using the recommended online method, you can secure your EIN quickly and start focusing on your business. Remember to keep your information current with the IRS to avoid compliance issues. For personalized advice, consult a tax professional. Stay updated via IRS.gov for any 2026 changes, and apply early to ensure smooth tax filing.