An LLC number is usually one of two things: the federal Employer Identification Number (EIN) the IRS assigns to your business, or the entity identification number your state gave your LLC when you filed formation paperwork. The EIN is a nine-digit federal tax ID that functions like a Social Security number for the business. The state number is a tracking ID in the state’s business registry. Both come up routinely — on tax returns, bank applications, annual reports, license paperwork — and which one someone is asking for depends on the context.
EIN vs. State ID: Which Number Do You Need?
An EIN is a nine-digit number in the format XX-XXXXXXX that the IRS assigns to businesses, nonprofits, trusts, estates, and other entities required to file tax returns or report employment taxes.1Internal Revenue Service. Publication 1635 – Understanding Your EIN It identifies your LLC on every federal filing and IRS notice. You’ll need it to file federal returns, report and pay employment taxes if you have workers, open a business bank account, and apply for business credit or licenses.
Not every LLC has to have one. A single-member LLC treated by the IRS as a disregarded entity — the owner reports the business income on a personal return — can use the owner’s Social Security number, as long as the LLC has no employees and no excise tax obligations.2Internal Revenue Service. Single Member Limited Liability Companies In practice, most single-member LLCs get an EIN anyway. Banks require one to open a business account, some state tax authorities require one, and the moment you hire an employee or take on excise tax liability, you need one regardless.
The state number is different. When you filed your Articles of Organization or Certificate of Formation, the state agency — usually the Secretary of State — assigned your LLC a unique identifier. States use different labels: Entity ID, File Number, Control Number, Charter Number. It ties your LLC to its record in the state registry, and it appears on annual reports, amendments, registered agent filings, and the public business search. It has no federal tax significance. If someone at the state asks for your LLC number, they mean this one. If a federal form or a bank asks, they mean the EIN.
How to Get an EIN
Applying is free. The IRS specifically warns against sites that charge for it, and the FTC has flagged companies billing as much as $300 for a service you can complete yourself in minutes.3Internal Revenue Service. Get an Employer Identification Number
Have this ready before you start: the legal name and taxpayer ID (SSN or ITIN) of the “responsible party,” your LLC’s legal name and physical address, the date the business started, and the reason you’re applying. The responsible party has to be a real person who owns or controls the entity, not another business.4Internal Revenue Service. Instructions for Form SS-4 – Application for Employer Identification Number
Apply Online
The IRS online application at irs.gov is the fastest option and issues the EIN immediately once approved.3Internal Revenue Service. Get an Employer Identification Number It runs Monday through Friday, 7:00 a.m. to 10:00 p.m. Eastern. The session times out after 15 minutes of inactivity and there’s no way to save and return, so gather everything first.
Apply by Fax or Mail
You can also submit Form SS-4 by fax or mail. Faxed applications come back in about four business days. Mailed applications take roughly four weeks, and the IRS advises sending the form four to five weeks before you actually need the number.4Internal Revenue Service. Instructions for Form SS-4 – Application for Employer Identification Number
International Applicants
If you have no legal residence, principal place of business, or office in the U.S. or its territories, apply by phone at 267-941-1099 (not toll-free), Monday through Friday, 6:00 a.m. to 11:00 p.m. Eastern. The caller must be authorized to receive the EIN and answer questions about the SS-4, and should have the form filled in before calling.4Internal Revenue Service. Instructions for Form SS-4 – Application for Employer Identification Number Phone applications are not available to domestic filers.
Where Your EIN Already Appears
After the IRS assigns the EIN, it mails a one-page confirmation called Notice CP 575 to the address on your application. That letter is the cleanest proof of the number.5Internal Revenue Service. Employer Identification Number If you applied online, the number also appeared on the final screen. Save or print that page — a lot of owners close the tab and lose the record.
The EIN also lives on every federal return the LLC has filed, whether Form 1065 for a partnership or Form 1120 for a corporation, depending on how the LLC is taxed.6Internal Revenue Service. Instructions for Form 1120 Your business bank will have it on file, and it often shows up on bank statements and IRS notices.
Where Your State LLC Number Appears
Your state ID is on the approved Articles of Organization or Certificate of Formation the state returned after filing, and on every annual report, amendment, or other document you’ve filed with the Secretary of State since.
If those documents aren’t at hand, most states run a free business entity search on the Secretary of State’s website. Enter the LLC’s legal name and the results show the entity number along with formation date, status, and registered agent. That’s usually faster than requesting certified copies or calling the state office.
What to Do If You’ve Lost Your EIN
The IRS won’t send another CP 575, but it will issue a replacement called Letter 147C, which serves the same purpose as proof of your EIN. Call the Business and Specialty Tax Line at 800-829-4933, Monday through Friday, 7:00 a.m. to 7:00 p.m. local time (Alaska and Hawaii use Pacific time).5Internal Revenue Service. Employer Identification Number After identity verification, the representative can read the EIN to you, fax the 147C while you’re on the line, or mail it — the mailed copy takes four to six weeks.
Before you call, try the faster routes the IRS suggests: past business tax returns, the bank holding your business account, or any state or local license application where you’d have listed the EIN.5Internal Revenue Service. Employer Identification Number You can also request a business entity transcript from the IRS, which lists the EIN on file.
When a Change to Your LLC Requires a New EIN
Not every change forces a new number. The IRS draws a clear line: certain shifts in ownership or structure require a new EIN; routine administrative changes do not.7Internal Revenue Service. When to Get a New EIN
You need a new EIN if you terminate an existing LLC and form a new corporation or partnership, or if your single-member LLC becomes liable for employment or excise taxes and has been using your personal SSN.
You do not need a new EIN if you change the LLC’s name or address — notify the IRS by letter or by checking the appropriate box on your next return.8Internal Revenue Service. Business Name Change You also keep the same EIN when a partnership converts to an LLC still classified as a partnership, when you elect corporate or S corporation tax treatment, or when you carry a sole proprietor EIN into a single-member LLC (provided you haven’t elected corporate status and have no employees or excise tax obligations).
Keeping Your EIN Safe
Business identity theft using stolen EINs is common, and it usually shows up as fraudulent tax filings rather than credit card fraud. Warning signs: an e-filed return rejected because the IRS already has one on record for that period, notices about returns or W-2s you didn’t file, or a balance-due notice for tax you don’t owe.9Internal Revenue Service. Report Identity Theft for a Business If any of those appear, file Form 14039-B (Business Identity Theft Affidavit) with the documentation the IRS requests. Only file it when there’s evidence of actual fraudulent filings tied to your EIN, not for a data breach on its own.
Day to day, treat the EIN with the same care as a Social Security number. Don’t publish it, and be skeptical of anyone asking for it who isn’t your bank, a government agency, or a party you’re actively doing business with.