Status: research-only. Nothing here is legal or tax advice. Before applying for an EIN or any state tax ID, confirm timing and designations with a CPA — in particular, the "responsible party" designation on Form SS-4 has downstream consequences.
Last updated: 2026-04-22. Verify against primary IRS and state-agency sources at filing time.
TL;DR
A federal Employer Identification Number (EIN) is a 9-digit federal tax ID applied for via Form SS-4. For a US-principal-place-of-business entity, the online application is free, takes about 15 minutes, and issues an EIN immediately. Apply after state entity formation is complete — the online system will ask for the entity's legal name exactly as filed with the state. Only one EIN per responsible party per day is allowed. State-level tax IDs (sales tax, employer withholding, unemployment) are separate from the federal EIN and are issued by state agencies — timing and requirements vary by state.
Facts (with citations)
EIN is free. The IRS issues EINs at no cost. The IRS online EIN page explicitly warns: "Beware of websites that charge for an EIN. You never have to pay a fee for an EIN." [1]
Form SS-4 is the underlying application. [2]
Online application eligibility. You can use the online EIN application if:
Your principal place of business is in the US or US territories, AND
You are the responsible party in control of the entity (or their authorized representative), AND
You have the responsible party's Social Security Number or Individual Taxpayer ID Number (ITIN).
You cannot use the online tool if your principal place of business is outside the US (those applicants apply by phone, fax, or mail). [1]
Immediate issuance. The online system issues the EIN immediately upon approval and provides a downloadable confirmation letter. [1]
Session constraints. The online application must be completed in one session; it cannot be saved. The session expires after 15 minutes of inactivity. [1]
Daily limit.One EIN per responsible party per day. [1]
Operating hours. The online EIN system is available Mon–Fri 6:00 a.m. – 1:00 a.m. (next day), Sat 6:00 a.m. – 9:00 p.m., Sun 6:00 p.m. – 12:00 a.m. (Eastern). [1]
When to apply. The IRS explicitly instructs: "If you are forming a legal entity (LLC, partnership, corporation or tax exempt organization), form your entity through your state before you apply for an EIN. If you don't form your entity with your state first, your EIN application may be delayed." [1]
Responsible party. The SS-4 requires a natural-person "responsible party" with SSN or ITIN — usually the principal officer, general partner, or owner-of-record. This person is the IRS's point of contact for the entity.
FinCEN BOI reporting. The IRS EIN page notes: "Some corporations, limited liability companies, and other entities may be required to report information on beneficial owners (the people who ultimately own or control the company) to the U.S. Department of the Treasury's Financial Crimes Enforcement Network (FinCEN)." [1] BOI enforcement status has been volatile — verify with your attorney or CPA at formation time.
Filing path — recommended sequence
Form the state entity first. File Articles of Organization / Certificate of Formation with the state (see state-of-formation.md). Obtain a filed Certificate / stamped filing showing the entity's exact legal name and state file number.
Decide on tax classification. A single-member LLC defaults to disregarded-entity treatment but can elect S-Corp later. The SS-4 has a checkbox for "LLC" with sub-questions about members — answer truthfully as the state-filed entity today; tax classification is changed later via Form 2553 or Form 8832.
Apply for the EIN online at https://www.irs.gov/businesses/small-businesses-self-employed/apply-for-an-employer-identification-number-ein-online. [1]
Save the EIN confirmation letter (CP 575 equivalent) as a PDF immediately — the online system will not resend it later. If lost, you request a replacement (147C letter) by calling the IRS Business & Specialty Tax Line.
State-level tax registrations. Follow up with the home-state Department of Revenue / taxation agency for any of the following that apply:
- Sales tax / seller's permit — if Raxx is collecting sales tax on SaaS subscriptions. Many states now tax SaaS; home-state rules vary dramatically. (Stripe Tax, referenced in issue #127, can help compute obligations once sales are happening.)
- Employer withholding account — required once you have a W-2 employee (including yourself as an S-Corp shareholder-employee after the 2553 election).
- Unemployment insurance — required as part of payroll setup, handled by the payroll provider in most cases.
- State business license / local business license — required in many states/cities regardless of entity type. Verify with the home-state SOS and city clerk.
Open the business bank account. Banks will ask for the state formation certificate, the EIN confirmation letter, and an operating agreement (for LLCs). This is a non-IRS step but usually happens next.
Jurisdiction flags
Federal EIN is uniform — same Form SS-4, same issuing agency, across all US states.
State tax IDs vary wildly. Same entity will typically have:
1 federal EIN
1 state income-tax account (if the state has corporate or pass-through tax)
1 state sales-tax permit (if applicable)
1 state employer withholding account (if employing — includes S-Corp owner as W-2)
1 state unemployment insurance account (if employing)
Sales tax on SaaS. Some states treat SaaS as a taxable service or taxable product; some do not. Representative examples (verify each with the state agency and/or a sales-tax CPA): NY taxes SaaS as prewritten software; TX taxes SaaS (20% exemption for data-processing); CA generally does not tax SaaS; WA taxes some SaaS. This is a deeper research area — flag for a sales-tax specialist or a tool like Stripe Tax / Avalara.
Economic nexus. Post-Wayfair, even fully-remote SaaS triggers state sales-tax obligations in a state once a revenue or transaction threshold is crossed — typically $100k in sales or 200 transactions annually. This is a post-revenue concern; not urgent pre-launch but must be on the roadmap.
Timing / deadlines
No deadline to obtain an EIN, but the entity cannot open a bank account, run payroll, or file an S-Corp election without one — so in practice, get it immediately after state formation.
Form 2553 S-Corp election depends on the EIN — you cannot file 2553 before the EIN is issued. See owner-compensation.md for the 2553 deadline (March 15 for calendar-year entities).
BOI report — Corporate Transparency Act reporting deadlines depend on entity formation date and current enforcement posture. Confirm with your attorney at formation time.
Questions for your CPA
Should the single-member LLC (if that's the formation choice) be registered for federal employer withholding on day 1, or only after an S-Corp election triggers payroll?
Is there a state-level tax-registration sequence I should follow in order to minimize double-registering?
Does Raxx's SaaS subscription revenue trigger sales tax in my home state, and at what volume?
Do you recommend any tax-prep software or tools that integrate cleanly with Stripe / QuickBooks for a single-member LLC / S-Corp?
What's the "responsible party" update process if that changes later (e.g., a co-founder joins)?
Questions for your business-formation attorney
Who should be named as the "responsible party" on Form SS-4 — me personally, or is there a scenario where a registered agent or another party should be listed?
Any operating-agreement / corporate-resolution steps that should be complete before the EIN application?
Current FinCEN BOI reporting requirement for a new LLC formed this year — is it required, and do you handle the filing or is it DIY?
Sources
IRS — Get an Employer Identification Number (free, online, immediate; eligibility; one-per-day limit; session constraints; operating hours; form-state-first; FinCEN BOI note). https://www.irs.gov/businesses/small-businesses-self-employed/apply-for-an-employer-identification-number-ein-online
IRS — About Form SS-4, Application for Employer Identification Number (EIN). https://www.irs.gov/forms-pubs/about-form-ss-4
Do not apply for an EIN, register for state tax IDs, or designate a responsible party without first discussing with a CPA and your business-formation attorney. This document is preparation material only.