Your LLC tax ID number is almost certainly an Employer Identification Number, or EIN — a nine-digit number the IRS assigns to your business. If your LLC already has one, it appears on the original IRS confirmation notice (CP 575), on past federal tax returns, and on the paperwork you used to open a business bank account. If you still need one, apply free at irs.gov and you’ll get the number immediately.
What the Number Actually Is
Federal law requires any entity that isn’t an individual to use an EIN as its taxpayer identifying number.1Office of the Law Revision Counsel. 26 USC 6109 – Identifying Numbers The format is two digits, a hyphen, then seven digits, like 12-3456789. Once the IRS issues an EIN, it belongs to that entity permanently. The number is never recycled or reassigned, even if the business shuts down.2Internal Revenue Service. If You No Longer Need Your EIN
There is one exception for LLCs. A single-member LLC with no employees and no excise tax liability is treated as a “disregarded entity,” and the owner can use their own Social Security Number instead of getting a separate EIN. The LLC’s income and expenses flow straight onto the owner’s personal return.3Internal Revenue Service. Single Member Limited Liability Companies The moment that LLC hires an employee or picks up excise tax obligations, it has to get its own EIN.4Internal Revenue Service. When to Get a New EIN Multi-member LLCs always need an EIN, because the IRS treats them as partnerships by default and a partnership can’t file under an individual’s SSN.
One boundary worth naming: your EIN is a federal number. States issue their own tax IDs for sales tax permits and employer accounts if your LLC triggers them, and those are separate from your EIN and handled by state revenue or labor agencies.
How to Find Your Existing EIN
Several places carry the number.
The CP 575 Notice
When the IRS first assigns an EIN, it mails a confirmation letter called Notice CP 575 to the address on file. That letter is the most authoritative record you have.5Internal Revenue Service. Tax Topic 654 – Understanding Your CP 575 The IRS only issues CP 575 once. If you’ve lost yours, request a replacement called a 147C verification letter by calling the Business and Specialty Tax Line at 800-829-4933, Monday through Friday, 7 a.m. to 7 p.m. your local time.6Internal Revenue Service. Telephone Assistance Contacts for Business Customers The agent will verify your identity, then fax or mail the 147C.
Your Own Records
The EIN is on previously filed federal returns — Form 1065 for partnerships, Form 1120 for corporations — plus quarterly payroll reports and the paperwork your business bank kept when you opened the account. Local business licenses and state permit registrations usually list it too.
What You Need Before You Apply
If you don’t have an EIN yet, gather this information first. It all feeds into Form SS-4, the official application.7Internal Revenue Service. Instructions for Form SS-4 (12/2025)
- The LLC’s legal name, exactly as written on the articles of organization you filed with your state. Small differences matter — abbreviating “LLC” when the formation document spells out “Limited Liability Company” can cause a rejection.
- A responsible party: one individual who controls or manages the LLC, along with their SSN or ITIN. Nominees are not allowed.8Internal Revenue Service. Responsible Parties and Nominees
- A physical U.S. mailing address where the IRS can send notices.
- Basic structure details: number of members, formation date, and the reason you need the EIN (new business, hiring, banking, and so on).
You don’t need to submit a paper SS-4 if you apply online, but filling one out as a reference makes the online questions go faster.
How to Apply
The IRS charges nothing for an EIN. Every application method is free, and any site asking you to pay is not the IRS.9Internal Revenue Service. Get an Employer Identification Number You’re limited to one EIN per responsible party per day.10Internal Revenue Service. Employer Identification Number
Online
The IRS EIN Assistant at irs.gov walks you through the questions and issues the number immediately on approval. The tool is available Monday through Friday from 6 a.m. to 1 a.m. the next day, Saturday from 6 a.m. to 9 p.m., and Sunday from 6 p.m. to midnight, all Eastern Time.9Internal Revenue Service. Get an Employer Identification Number The responsible party needs a valid U.S. SSN or ITIN to use it.
Fax
Fax the completed Form SS-4 to the IRS. If you include a return fax number, you’ll usually get the EIN back within four business days.7Internal Revenue Service. Instructions for Form SS-4 (12/2025)
Mailing is the slowest. The IRS says to submit at least four to five weeks before you need the number, because processing plus return mail runs about four weeks.7Internal Revenue Service. Instructions for Form SS-4 (12/2025)
Foreign Applicants
If the responsible party has no SSN or ITIN and isn’t eligible for one, enter “foreign” or “N/A” on Line 7b of Form SS-4.7Internal Revenue Service. Instructions for Form SS-4 (12/2025) The online tool won’t work without a U.S. taxpayer ID. International applicants with no legal residence or principal place of business in the United States can apply by phone at 267-941-1099 (not toll-free), Monday through Friday, 6 a.m. to 11 p.m. Eastern. The caller must be authorized to receive the EIN and answer questions about the form. After the IRS assigns the number by phone, it may ask you to mail or fax the signed SS-4 within 24 hours. Fax and mail also work using the addresses designated for applicants outside the U.S., with the same four-business-day and four-week timelines.
When You Need a New EIN — and When You Don’t
Most routine changes don’t trigger a new number. Your LLC keeps the same EIN if it changes names, moves, or switches its tax election between partnership and corporate treatment.4Internal Revenue Service. When to Get a New EIN
You do need a new EIN in two cases:
- You dissolve the existing LLC and form a new corporation or partnership. The new entity gets its own number.
- A single-member LLC that has been using the owner’s SSN now has to file employment or excise tax returns. At that point the LLC needs its own EIN.
Keep the Responsible Party Current
When the person who controls or manages the LLC changes, notify the IRS within 60 days on Form 8822-B. The same form handles address changes.11Internal Revenue Service. About Form 8822-B, Change of Address or Responsible Party This gets missed often when members buy in or out. If the responsible party on file is out of date, an IRS agent won’t release account information over the phone, because they verify against that record.
Watch Out for Paid Application Sites
The IRS has said plainly that there is never a fee to obtain an EIN.9Internal Revenue Service. Get an Employer Identification Number Third-party sites nevertheless charge up to $300 to submit the same free application, and many mimic official government pages. The FTC has flagged operators using IRS-style logos, color schemes, and domain names containing “IRS” to imply government affiliation, often without clearly disclosing that they are not the IRS and that their fee buys nothing the IRS doesn’t provide free.12Federal Trade Commission. FTC Warns Operators of Websites that Charge for an Employer Identification Number and Claim Affiliation with the IRS Go directly to irs.gov and look for the tool called EIN Assistant. If a page asks for payment before issuing a number, it isn’t the IRS.