An LLC number is one of two IDs people commonly mean by that phrase: the federal Employer Identification Number (EIN) the IRS assigns for tax purposes, or the entity identification number your state gives your LLC when you file its formation documents. The EIN is a nine-digit federal tax ID that works like a Social Security number for the business. The state number tracks your LLC in the official business registry where it was formed. You’ll run into both when filing taxes, opening a bank account, or handling routine compliance, so it helps to know which one a given form is asking for.
The Two Numbers, Side by Side
The EIN comes from the IRS and follows the format XX-XXXXXXX.1Internal Revenue Service. Publication 1635 – Understanding Your EIN It’s what the IRS uses to identify your business across every return, notice, and payment. You’ll need it to file federal income tax returns, report and pay employment taxes if you hire anyone, open a business bank account, and apply for business credit or most licenses.
The state ID is assigned by the filing agency, usually the Secretary of State, when you submit your Articles of Organization or Certificate of Formation. States label it differently: Entity ID, File Number, Control Number, Charter Number. It’s what state agencies use on annual reports, amendments, and registered agent filings, and it’s the number the public sees when they look up your LLC in the state’s online business database. It has no federal tax significance.
When a Single-Member LLC Can Skip the EIN
Not every LLC needs its own EIN. A single-member LLC that the IRS treats as a disregarded entity, meaning the owner reports the business income on their personal return, can use the owner’s Social Security number instead, as long as the LLC has no employees and no excise tax obligations.2Internal Revenue Service. Single Member Limited Liability Companies Most single-member owners still get one, because banks generally require an EIN to open a business account and some state tax authorities require it too. The moment you hire someone or pick up an excise tax liability, you need an EIN regardless.
How to Get an EIN
Applying is free. The IRS warns against third-party sites that charge for what you can do yourself in minutes at no cost.3Internal Revenue Service. Get an Employer Identification Number
Have this ready before you start: the full 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 is the individual who ultimately owns or controls the entity and can direct its funds and assets, and it must be a real person, not another business.4Internal Revenue Service. Instructions for Form SS-4 – Application for Employer Identification Number If that person has no SSN or ITIN and can’t get one, enter “foreign” or “N/A.”
The fastest route is the IRS online application, which issues the EIN immediately when you finish.3Internal Revenue Service. Get an Employer Identification Number It’s open Monday through Friday, 7:00 a.m. to 10:00 p.m. Eastern. The session times out after 15 minutes of inactivity and can’t be saved, so gather everything first.
If you can’t use the website, submit Form SS-4 by fax and you’ll generally get the EIN back in about four business days. Mail takes roughly four weeks to deliver, and the IRS suggests filing at least four to five weeks before you need the number.4Internal Revenue Service. Instructions for Form SS-4 – Application for Employer Identification Number
Applicants with no legal residence, principal business location, or office in the U.S. or its territories can apply by phone at 267-941-1099 (not toll-free), Monday through Friday, 6:00 a.m. to 11:00 p.m. Eastern. Fill out Form SS-4 before calling; the representative walks through it and assigns the EIN on the call.4Internal Revenue Service. Instructions for Form SS-4 – Application for Employer Identification Number Phone applications aren’t open to domestic applicants.
How to Find an EIN You Already Have
After the IRS assigns an EIN, it mails a one-page confirmation called Notice CP 575 to the address on the application. That letter is the cleanest proof of your number.5Internal Revenue Service. Employer Identification Number If you applied online, the EIN also appeared on screen at the end of the session. Many owners close that tab and lose it, so print or save the confirmation page.
The EIN also lives on every federal tax return your LLC has filed, whether that’s Form 1065 or Form 1120 depending on tax classification.6Internal Revenue Service. Instructions for Form 1120 Your bank has it on file, and it often shows up on statements and IRS correspondence.
If none of that works, the IRS won’t send another CP 575, but it will issue a replacement called Letter 147C that serves the same purpose. 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). After identity verification, an authorized caller can have the EIN read over the phone or the 147C faxed during the call. A mailed copy takes four to six weeks. Before calling, try the shortcuts the IRS suggests: past tax returns, the business bank, or state and local license applications where you listed the EIN.5Internal Revenue Service. Employer Identification Number
How to Find Your State LLC Number
Your state-issued number is printed on the approved copy of your Articles of Organization or Certificate of Formation that the state returned after filing. It also appears on any annual reports, amendments, or other filings you’ve made with the Secretary of State since.
Lost those? Most states run a free online business entity search on the Secretary of State’s website. Enter the LLC’s legal name and the results show the entity number, formation date, status, and registered agent. It’s usually faster than requesting certified copies or calling the agency.
When You Need a New EIN (and When You Don’t)
People often assume any change to the LLC means a new EIN. It doesn’t. The IRS reserves new EINs for specific changes in ownership or structure and lets routine administrative updates ride on the existing number.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 you own a single-member LLC that becomes liable for employment or excise taxes and has been running on your personal SSN.
You do not need a new EIN if you change the LLC’s name or location (notify the IRS by letter or by checking the box on your next return),8Internal Revenue Service. Business Name Change convert a partnership to an LLC still classified as a partnership, or change your tax election to a corporation or S corporation. A sole proprietor’s EIN can even carry over to a single-member LLC, as long as you haven’t elected corporate or S corporation status and don’t have employees or excise tax obligations.
Keeping Your EIN Safe
Business identity theft using an EIN typically shows up as fraudulent tax returns or fake W-2s filed against your business, not new credit cards. Watch for e-file rejections because a return is already on file for the period, notices about returns or W-2s you didn’t file, and balance-due notices for taxes you don’t owe.9Internal Revenue Service. Report Identity Theft for a Business If any of that happens, file Form 14039-B (Business Identity Theft Affidavit) with the requested documentation. The IRS says not to file it for a data breach alone, only when there’s evidence of actual fraudulent filings tied to your EIN.
Treat the EIN like a Social Security number. Limit who has it, don’t post it publicly, and be skeptical of any request that doesn’t come from a bank, government agency, or party you’re actively doing business with.