Your LLC’s federal tax ID number, formally called an Employer Identification Number, is a nine-digit number the IRS issues in the format 12-3456789. If you need to find your LLC tax ID number, the fastest places to look are the original IRS confirmation letter, any federal tax return your business has filed, your business bank paperwork, and any state or local license application. If none of those turn it up, the IRS will read it back to you over the phone.
The Original IRS Confirmation Letter (CP 575)
When your EIN was issued, the IRS sent a CP 575 notice showing the number, your LLC’s legal name, and the mailing address on file. If you applied online, the notice appeared at the end of the application and you were prompted to print or save it. Fax applicants got theirs back by return fax within about four business days; mailed applications took roughly four weeks.
Check your filing cabinet, your downloads folder, and your saved email attachments first. The CP 575 is the single most authoritative proof of your EIN, and the IRS only issues it once. If you’ve lost it, the replacement is a 147C verification letter, which you request by phone (see below).
Past Federal Tax Returns
Every federal return your LLC has filed prints the EIN on the first page. Which form to pull depends on how the IRS classifies the LLC:
- Multi-member LLC taxed as a partnership: Item D on the first page of Form 1065.1Internal Revenue Service. Form 1065 – U.S. Return of Partnership Income (2025)
- LLC taxed as a corporation: Item B on Form 1120 (C-corp) or Form 1120-S (S-corp).2Internal Revenue Service. Instructions for Form 1120 (2025) – Section: General Instructions
- Single-member LLC reporting on Schedule C of Form 1040: Line D.3Internal Revenue Service. 2025 Instructions for Schedule C (Form 1040)
- Members of a multi-member LLC: the partnership’s EIN appears on your annual Schedule K-1.4Internal Revenue Service. Shareholder’s Instructions for Schedule K-1 (Form 1120-S) (2025)
One thing to watch for with single-member LLCs: some never obtained a separate EIN because they weren’t required to, and they report business income under the owner’s Social Security number. If Line D on your Schedule C is blank, that’s likely what’s happening, and there is no EIN to find.
State franchise tax returns and annual reports generally repeat the same federal EIN, so those filings are worth a look too.
Business Bank and Financing Records
Federal regulations require banks to collect an identification number before opening any business account.5eCFR. 31 CFR 1020.220 – Customer Identification Program Requirements for Banks Your EIN has been sitting in the bank’s records since the day the account opened. Places to check:
- Your online banking portal, under a “business profile,” “account details,” or “settings” area.
- The original account application and signature card.
- Business credit card agreements, SBA loan paperwork, and lines of credit.
If none of those are within reach, call the bank. Once they confirm you’re an authorized signer, they can read the number back to you.
State and Local License Applications
Most state and local permit applications ask for the federal EIN before they’ll process anything, including general business licenses, sales tax permits, and professional registrations.6U.S. Small Business Administration. Get Federal and State Tax ID Numbers Any license you have displayed at your business or filed with the Secretary of State likely shows the number on the application copy.
Call the IRS if Nothing Else Works
When the paper trail runs dry, the IRS will give the number over the phone. 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 follow Pacific time).7Internal Revenue Service. Telephone Assistance Contacts for Business Customers
The agent will only release the EIN to someone authorized to receive it, meaning a managing member, an officer listed on the original application, or a sole proprietor. Be ready to answer identity-verification questions about the business address on file and the Social Security numbers of the owners. Wrong answers end the call.
While you have the agent on the line, ask for a 147C verification letter. It’s the IRS’s official replacement for the CP 575, can be faxed to you the same day, and carries the same weight as the original notice with banks and licensing agencies that won’t accept anything else as proof.
If a Representative Is Calling for You
A tax professional or other representative can retrieve the EIN on your behalf only if the IRS already has their authorization on file. Form 8821 (Tax Information Authorization) lets a designated person receive your tax information, including your EIN.8Internal Revenue Service. About Form 8821, Tax Information Authorization Form 2848 (Power of Attorney) grants broader authority to act on your behalf before the IRS. File the form before the representative calls, not after.