Form SS-4: How to Apply for an EIN by Mail or Fax in 2026

Form SS-4 is the IRS application for an Employer Identification Number, the nine-digit number your business needs to open a bank account, hire employees, or file taxes. Most guides send you straight to the IRS online EIN Assistant, which works for most US-based founders. But if you don't have a Social Security number, an ITIN, or an existing EIN as the responsible party, the online tool will reject you outright, and you need the paper form instead. Here's how to fill it out and get it to the IRS by fax or mail.

Who Can (and Can't) Use the Online EIN Assistant

The IRS EIN Assistant at IRS.gov is free, instant, and works for most domestic applicants. It issues an EIN immediately once you finish the interview. The catch is one requirement buried in the fine print: the responsible party listed on the application must already have a valid SSN, ITIN, or EIN of their own, and the tool checks that number against IRS records before it will proceed.

That excludes a specific but common group of applicants: a non-US resident forming a foreign-owned single-member LLC, a founder who hasn't yet applied for an ITIN, or anyone whose principal business address is outside the United States. According to the IRS's own instructions for Form SS-4, these applicants must apply by fax, mail, or phone instead. If the online assistant tells you it "cannot process this request" or asks for a US taxpayer identification number you don't have, that's your sign to switch to the paper form covered below.

What You Need Before Filling Out Form SS-4

Gather this before you start so you don't have to stop halfway through:

• The legal name and mailing address of the entity applying (your LLC, corporation, trust, or estate).
• The entity's responsible party: the person who ultimately owns or controls it, along with their SSN, ITIN, or EIN if they have one.
• The state or country where the entity was formed, and the date it was formed.
• The reason you're applying (started a new business, hired employees, banking purposes, changed organization type, and so on).
• The type of entity (LLC, corporation, partnership, sole proprietor, trust) and, for an LLC, how many members it has and whether it will be taxed as a corporation or disregarded entity.

You can download the current version of Form SS-4 directly from IRS.gov, then upload it at Fill PDF to complete every field in your browser instead of printing it blank and writing by hand.

Step by Step: Filling Out the PDF

1. Lines 1-3: Legal name and trade name. Line 1 is the entity's exact legal name as it appears on formation documents. Line 2 is only for a trade name or DBA, and Line 3 is for the executor, administrator, or trustee name if you're applying for an estate or trust.
2. Lines 4a-6: Addresses. Line 4a/4b is the mailing address where the IRS will send your confirmation letter. Line 5a/5b is only needed if the business's physical location differs from the mailing address. Line 6 is the county and state (or country, if outside the US) where the business is principally located.
3. Line 7a-7b: Responsible party. Enter the full name of the responsible party on 7a, then their SSN, ITIN, or EIN on 7b. If the responsible party is a non-US person who does not have and is not eligible for an SSN or ITIN, the IRS instructions allow you to write "Foreign" on 7b instead of leaving it blank. A blank 7b is one of the most common reasons applications get bounced back.
4. Lines 8a-9a: Entity type. Check the one box that matches your structure. For an LLC, Line 8a asks if it's an LLC, 8b asks how many members, and 8c asks if it was organized in the US. Line 9a is where you pick how the LLC (or other entity) will be classified for tax purposes.
5. Lines 10-15: Reason and dates. Line 10 is why you're applying (most new businesses check "Started new business"). Line 11 is the date the business started or was acquired. Lines 12-15 cover your accounting year end, expected number of employees, and first date wages will be paid, if applicable.
6. Line 16-17: Business activity. Describe the principal activity in plain language ("e-commerce retail," "software consulting") and the specific product or service.
7. Line 18 and signature. Answer whether the entity has applied for an EIN before, then sign, print your name and title, and add a daytime phone number. If you want a third-party designee (like an accountant) to receive the EIN on your behalf, fill in that box above the signature line, but note this does not replace the responsible party information on Line 7.

Once every field is filled in, add your signature directly on the PDF with Sign PDF so the form is ready to fax or print without a separate scanning step.

Fax vs Mail: Which Is Faster

Fax is significantly faster than mail for Form SS-4, and which fax number you use depends on where the business is located:

These addresses and fax numbers are current per the IRS's December 2025 instructions for Form SS-4; always cross-check against the latest version at IRS.gov before sending, since the IRS updates these periodically. If you're outside the US and don't have fax access, international applicants can also call 267-941-1099 (not toll-free), Monday through Friday, 6 a.m. to 11 p.m. Eastern time, to apply by phone.

Include a fax cover sheet with your callback number so the IRS can reach you if a field is unclear, and keep the fax confirmation page. If you mail it instead, keep a copy of the signed form for your own records since the IRS won't send one back.

Common Rejections and How to Avoid Them

• Blank Line 7b. Leaving the responsible party's identifying number empty is a frequent cause of delay. Write "Foreign" if the person genuinely has no SSN or ITIN and isn't eligible for one, rather than leaving it blank.
• Vague answer on Line 10. "Other" without an explanation, or a reason that doesn't match the entity type you selected, can trigger a follow-up letter instead of an EIN.
• Mismatched entity name. The name on Line 1 has to match your formation documents (articles of organization, trust agreement) exactly, including punctuation and abbreviations.
• Missing signature or title. An unsigned SS-4, or one signed without a title (owner, member, trustee), gets sent back unprocessed.
• One EIN per responsible party per day. The IRS limits online and often paper issuance to one EIN per responsible party per business day; if you're applying for a second entity the same day, expect it to be held for review.

If you're setting up more than just this one form, gathering formation documents, filling SS-4, and signing a banking resolution, it helps to have all of it in one browser tab instead of switching between a PDF reader, a scanner, and email. A One Week Plan is a $3 one-time charge that covers exactly this kind of short setup task: fill, sign, and export everything you need for the new entity, then it simply expires with nothing to cancel, unlike a monthly subscription you'd have to remember to turn off once the paperwork is done.

FAQs

Can I apply for an EIN without a Social Security number?

Yes. If the responsible party doesn't have and can't obtain an SSN or ITIN, you can still apply for an EIN by fax, mail, or phone using Form SS-4, writing "Foreign" on Line 7b instead of a number.

How long does it take to get an EIN by fax?

Generally about four business days if you fax a correctly completed Form SS-4 to the number matching your location, compared to roughly four weeks by mail.

Do I need an ITIN before I can get an EIN?

No. An EIN and an ITIN are separate numbers issued for different purposes, and you can obtain an EIN for your business first even if you apply for a personal ITIN later.

What happens if I leave the responsible party's SSN or ITIN blank on Form SS-4?

The IRS may delay or reject the application. If the responsible party is a foreign national with no SSN or ITIN and no eligibility to get one, write "Foreign" rather than leaving the field empty.

Can someone else submit Form SS-4 on my behalf?

Yes, by listing them as a third-party designee in the box above the signature line, but this doesn't replace the responsible party information required on Line 7, which must still identify the entity's actual owner or controller.