Getting an EIN for an S corp is free and fast: apply through the IRS online EIN Assistant at irs.gov and the number is issued on screen at the end of the session, usually in about 15 minutes. If the responsible party does not have a Social Security Number or ITIN, you file Form SS-4 by fax (about four business days) or by mail (about four weeks) instead.1Internal Revenue Service. Get an Employer Identification Number Do this before you file Form 2553 to elect S corporation status, because the election form asks for the EIN on its first page.2Internal Revenue Service. IRS Form 2553 – Election by a Small Business Corporation
How to Apply
Three channels are open, and they lead to the same nine-digit number.
Online. The IRS EIN Assistant walks you through an electronic Form SS-4 and issues the EIN immediately when you finish. To qualify, the corporation must be a domestic entity and the responsible party must have a valid SSN or ITIN. The tool runs Monday through Friday from 6:00 a.m. to 1:00 a.m. Eastern, Saturday from 6:00 a.m. to 9:00 p.m., and Sunday from 6:00 p.m. to midnight. The IRS limits issuance to one EIN per responsible party per day.1Internal Revenue Service. Get an Employer Identification Number
Fax. Complete a paper SS-4, include a return fax number, and send it to the IRS Fax-TIN service. Turnaround is generally within four business days.3Internal Revenue Service. Instructions for Form SS-4 (Rev. December 2025)
Mail. Sending the paper SS-4 by mail takes about four weeks. Fax numbers and mailing addresses depend on the applicant’s state, so check the current SS-4 instructions before sending. Illegible or incomplete forms come back.
What to Have Ready Before You Start
Whether you use the online tool or a paper form, the fields are the same. Pull these together first:
- The corporation’s full legal name and address, spelled exactly as they appear on the Articles of Incorporation filed with the state. A mismatch causes rejection.
- The responsible party’s name and SSN or ITIN. For a single-shareholder S corp, this is usually the sole owner. It goes on Lines 7a and 7b of Form SS-4.4Internal Revenue Service. Form SS-4 (Rev. December 2025)
- Entity type. On Line 9a, check “Corporation” and enter 1120-S as the form you will file.4Internal Revenue Service. Form SS-4 (Rev. December 2025)
- Reason for applying. “Started New Business” fits most new corporations.
- Business start date and the closing month of your accounting year.
- Expected number of employees in the next 12 months.
You can authorize a third-party designee, such as an attorney or accountant, to receive the EIN and answer IRS questions about the application. That authorization ends the moment the IRS releases the EIN to the designee.5Internal Revenue Service. Instructions for Form SS-4 (Rev. December 2025)
Get the EIN Before You File Form 2553
The S corp election runs on a tight clock. Form 2553 must be filed no later than two months and 15 days after the beginning of the tax year the election is to take effect, or at any time during the preceding tax year.6Internal Revenue Service. Instructions for Form 2553 Miss that window and the election slides to the following tax year, leaving the corporation taxed as a C corp in the meantime.
Because Form 2553 requires the EIN on its first page, mailing the SS-4 and waiting a month for the number can eat most of the election window.2Internal Revenue Service. IRS Form 2553 – Election by a Small Business Corporation If you qualify to apply online, use that channel and get the EIN the same day.
When You Need a New EIN and When You Do Not
The rules depend on what entity you are starting from:7Internal Revenue Service. When to Get a New EIN
- A sole proprietor incorporating needs a new EIN. The legal entity changed from an individual to a corporation.
- An LLC electing to be taxed as an S corp does not need a new EIN. The IRS treats this as the same entity changing its tax classification.
- An existing corporation electing S corp status does not need a new EIN. Choosing S corp taxation does not change the underlying entity.
- A new corporation formed by a merger needs its own new EIN.
Changing the corporation’s name or moving the principal office does not require a new EIN either. Those are updates to the existing record.7Internal Revenue Service. When to Get a New EIN
Save the CP 575 and Keep the Record Current
When the EIN is issued, download and print the CP 575 notice right away. The IRS issues this notice once and will not generate a duplicate. If it is lost, you call the IRS Business and Specialty Tax Line at 1-800-829-4933 and request a 147C verification letter as a replacement. Keep the CP 575 with the Articles of Incorporation and bylaws in the corporation’s permanent records.
If the responsible party changes, file Form 8822-B within 60 days. There is no penalty for late filing, but the IRS will send deficiency notices and demand letters to the old responsible party at the address on file, and interest and penalties accrue whether those notices reach anyone or not.8Internal Revenue Service. Form 8822-B, Change of Address or Responsible Party — Business A legal name change is reported by checking the “Name Change” box on the next Form 1120-S; no new EIN is needed.
Do Not Pay for an EIN
The IRS states plainly: “You never have to pay a fee for an EIN.”1Internal Revenue Service. Get an Employer Identification Number Websites charging $50 to $300 to file the same free application exist and often mimic IRS logos, formatting, and domain names. The only legitimate site for the online application is irs.gov.
Paid incorporation services and law firms that bundle EIN filing into a broader formation package are a different matter; there, you are paying for the full service. If a standalone site’s only product is filing your SS-4 for a fee, you are paying for something the IRS does for free in about 15 minutes.
Why the EIN Matters After You Have It
An S corporation still files its own return on Form 1120-S each year, even though income passes through to shareholders, and the IRS cannot process that return without an EIN tied to the corporation.9Internal Revenue Service. About Form 1120-S, U.S. Income Tax Return for an S Corporation The number also appears on quarterly Form 941 payroll returns and year-end W-2s.10Internal Revenue Service. Form 941 – Employer’s Quarterly Federal Tax Return Banks require the EIN to open a business account in the corporation’s legal name, which is one of the basic steps that keeps corporate funds separate from personal funds and preserves the liability shield.