Form SS-4

Sole Proprietor / Single-member LLC (disregarded entity)

One owner who reports business profit on Schedule C of their personal 1040. Most single-member LLCs default to this classification unless they elect otherwise.

Tip: You can use your SSN for taxes as a sole prop, but get an EIN anyway — most banks require one for a business checking account, and it lets you give clients a W-9 without exposing your SSN.

Partnership / Multi-member LLC

Two or more owners. Files Form 1065 federally and issues K-1s to each partner. Multi-member LLCs default to partnership classification.

Corporation (C-Corp)

Separate legal entity that files Form 1120 and pays its own income tax. Owners (shareholders) pay tax again on dividends — "double taxation."

S-Corporation

Pass-through corporation. Files Form 1120-S and issues K-1s. Requires a separate election (Form 2553) within 75 days of formation or the start of the tax year.

Tip: If you formed an LLC and want it taxed as an S-Corp, first get the EIN as a sole prop or partnership, then file Form 2553 to elect S-Corp status. Use the LLC vs S-Corp Calculator first to see if the election makes financial sense.

Estate / Trust

Estates of deceased individuals and most trusts need their own EIN to open accounts and file fiduciary returns (Form 1041).

Non-profit organization

Charities, churches, social welfare organizations, and similar. Getting an EIN is the first step; 501(c)(3) tax-exempt status requires a separate application (Form 1023 or 1023-EZ).

Who qualifies

A natural person — not another company. For an LLC, it's typically the sole member or the managing member. For a corporation, it's the principal officer (CEO, president). For a trust, it's the grantor or trustee.

Common mistake: Listing an attorney, CPA, or formation service as the responsible party. The IRS requires the actual owner. Third-party preparers can submit the application on your behalf but are NOT the responsible party.

SSN or ITIN required

The responsible party must provide a valid Social Security Number (SSN) or Individual Taxpayer Identification Number (ITIN).

Tip: Non-US persons without an SSN or ITIN cannot apply online. They must mail or fax the paper SS-4 with "Foreign" written in the SSN field — processing takes 4-6 weeks by mail or about 4 business days by fax.

Started a new business

The most common reason. Use this when you formed a new LLC, corporation, partnership, or sole proprietorship.

Hired employees

An existing business that now needs to file payroll taxes. Required even if you only hire one part-time employee.

Banking purposes

You need an EIN to open a business bank account. Common for solo sole props who otherwise could use their SSN.

Changed type of organization

Converted from sole prop to LLC, LLC to corporation, etc. The IRS may require a new EIN — check Publication 1635 for the rules on when a new EIN is required.

Other reasons

Created a trust, formed a non-profit, became a withholding agent, or are administering an estate. Each has its own option in the online flow.

URL

irs.gov/businesses/small-businesses-self-employed/apply-for-an-employer-identification-number-ein-online

Tip: Bookmark the IRS link directly. Searching "EIN application" turns up many paid services charging $50-$200 to fill out the same free IRS form on your behalf.

Hours of operation

Monday-Friday, 7am-10pm Eastern Time. The system is offline outside those hours and during scheduled IRS maintenance windows.

Session timeout

You have about 15 minutes of inactivity before the session expires. If it times out, you start over from the beginning.

Legal name and trade name

Legal name is what's on your formation documents (e.g., "Smith Consulting LLC"). Trade name is any DBA you use (e.g., "Acme Marketing"). Trade name is optional.

Mailing address and physical location

Use the address where the IRS should send correspondence. Many registered-agent services charge extra to receive IRS mail — using your home address or a US Postal Service PO Box is fine for most small businesses.

Start date / acquisition date

The date your business began operating or you acquired it. Doesn't have to match the formation date on your state filing.

Highest number of employees expected (next 12 months)

Zero is a valid answer. The IRS uses this to set your payroll filing schedule (Form 941 quarterly vs Form 944 annually). You can change it later.

Principal activity

Pick the closest match from the dropdown — Construction, Real Estate, Food Service, Retail, Wholesale, Healthcare, Professional Services, etc.

Save the CP 575 confirmation letter

At the end of the application, the system generates a PDF (Form CP 575) with your EIN and entity details. Download AND print it. This is your only proof of the EIN until the IRS sends the paper copy 4-6 weeks later.

Common mistake: Closing the browser tab without saving the PDF. The IRS won't email it. To get a replacement, you must call 1-800-829-4933 and request a verification letter (Form 147C) — they'll fax or mail it.

Tip: Save the CP 575 in two places: your accounting software AND a cloud drive. Banks, payroll providers, and vendors will all ask for it later.

Update your business records

Add the EIN to your accounting software (QuickBooks, Wave, Xero), payroll service, and the W-9 you send to clients. State tax IDs are separate — register with your state Department of Revenue if you have sales tax or payroll obligations.