IRS Form SS-4, officially titled “Application for Employer Identification Number (EIN),” is the key document used to obtain an EIN from the Internal Revenue Service (IRS). An EIN works like a Social Security number for your business, providing a unique identifier for federal tax administration. This helps the IRS track your business’s tax filings, payroll, and other financial activities.
What is an EIN?
An Employer Identification Number (EIN) is a nine-digit federal tax ID number issued by the IRS. It identifies your business entity for tax reporting purposes, distinguishing it from other businesses. Whether you are a corporation, partnership, LLC, or sole proprietor with employees, an EIN is often required for tax compliance. It enables you to file tax returns, report employment taxes, open bank accounts, and apply for business licenses.
Who Must File Form SS-4?
The IRS requires certain entities to obtain an EIN by submitting Form SS-4. Common scenarios include:
- Employers: If you pay wages to one or more employees, you must have an EIN for payroll tax reporting and withholding.
- Corporations and Partnerships: These legal entities must have an EIN regardless of employee status.
- Multi-Member LLCs: LLCs with multiple members generally need an EIN as they are taxed as partnerships.
- Tax-Exempt Organizations: Most nonprofits require an EIN to maintain tax-exempt status.
- Certain Trusts and Estates: Entities managing trusts or estates with taxable income often need an EIN.
- Entities filing excise or alcohol, tobacco, or firearms tax returns.
Sole proprietors without employees typically do not need an EIN and can use their Social Security number for tax reporting. However, obtaining an EIN can provide benefits such as business banking and personal privacy protection.
How to Apply for an EIN Using Form SS-4
The IRS offers four methods to apply for an EIN with Form SS-4:
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Online Application: The IRS EIN Online Assistant allows applicants with a principal place of business in the U.S. to receive their EIN immediately. This is the fastest and most convenient option. Keep in mind that only one EIN per responsible party can be obtained online per day.
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Fax: Submit your completed Form SS-4 via fax to the appropriate IRS fax number. If you provide a return fax number, the IRS usually responds within four business days.
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Mail: Mailing Form SS-4 is an option but is the slowest way to obtain an EIN, taking up to four weeks or longer.
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Telephone: International applicants without a U.S. office or principal place of business may apply for an EIN by calling the IRS Business & Specialty Tax Line.
When completing Form SS-4, provide accurate information such as legal business name, address, entity type, and the reason for applying. The “responsible party” must be clearly identified and the form signed.
Importance of an EIN
An EIN is essential for many business functions:
- Payroll and Employment Taxes: Required for reporting wages and withholding taxes.
- Business Banking: Most banks require an EIN to open business accounts.
- Tax Filings: Corporations, partnerships, and some LLCs must use an EIN on tax returns.
- Licensing and Permits: States often require an EIN to issue permits.
- Building Business Credit: An EIN helps establish your business credit profile.
- Protecting Privacy: Using an EIN in place of a Social Security number reduces personal exposure.
Common Mistakes to Avoid
- Mistakes or incomplete forms can delay EIN issuance.
- Applying for an EIN when not required can complicate records.
- Submitting multiple applications unnecessarily can lead to multiple EINs.
- Misidentifying the responsible party causes processing errors.
- Forgetting to sign the form results in rejection.
Quick Summary of EIN Application Options
| Method | Who Can Use It | Pros | Cons |
|---|---|---|---|
| Online | U.S.-based applicants | Instant EIN issuance | Limited to one EIN per responsible party daily |
| Fax | All applicants | Faster than mail; response in ~4 days | Requires fax access |
| All applicants | Can apply without internet or phone | Slowest method, takes weeks | |
| Telephone | International applicants without U.S. office | Enables international applicants | Only for international; phone required |
Frequently Asked Questions
Can I get an EIN instantly?
Yes. The IRS online application issues EINs immediately for applicants with a U.S. address.
Is an EIN required for sole proprietors?
Not always. Sole proprietors without employees can usually use their Social Security number. However, they may prefer an EIN for banking or privacy.
Can I correct errors after submitting Form SS-4?
Contact the IRS Business & Specialty Tax Line if errors are found before receiving an EIN. For changes post-issuance, a written request may be necessary.
Is there a fee to apply for an EIN?
No. The IRS charges no fee for EIN applications submitted directly. Avoid paid third-party services.
For detailed instructions and the latest forms, visit the official IRS page: IRS Form SS-4.
References:
- IRS. “About Form SS-4.” Accessed June 2025. https://www.irs.gov/forms-pubs/about-form-ss-4
- IRS. “Employer ID Numbers (EINs).” Accessed June 2025. https://www.irs.gov/businesses/small-businesses-self-employed/employer-id-numbers-eins
This comprehensive overview of Form SS-4 explains how to apply for your EIN, why it’s required for many businesses, and how to navigate the application process efficiently to keep your business compliant with IRS regulations.