When you’re using your EIN on business tax returns and other federal filings, enter the nine-digit number in the standard XX-XXXXXXX format in the header of every form, exactly as it appears on your SS-4 confirmation letter or IRS Notice CP 575, and pair it with the same legal name (or registered trade name) you gave when you applied. Federal regulations require the number on any return or statement submitted to the IRS.1eCFR. 26 CFR 301.6109-1 – Identifying Numbers Getting it right on every filing is what prevents the mismatches that stall processing and trigger penalties.
Do You Actually Need an EIN
Not every business owner needs one. Sole proprietors without employees can generally use their Social Security Number for federal filings. The IRS requires an EIN if you have employees, withhold taxes on payments to a nonresident alien, owe excise taxes, or operate as a partnership, LLC, corporation, S corporation, tax-exempt organization, estate, most kinds of trust, or a retirement plan.2Internal Revenue Service. Employer Identification Number
A single-member LLC taxed as a disregarded entity is the common edge case: it generally uses the owner’s SSN unless it has employees or owes excise taxes.
Entering the EIN and Name Correctly
The EIN sits in the header of virtually every federal form. Copy it directly from your SS-4 confirmation or Notice CP 575 so the digits and dash placement match IRS records. If a return comes due before your EIN arrives, write “Applied For” and the date of your application in the EIN space. Do not leave it blank, and do not substitute your Social Security Number.3Internal Revenue Service. Instructions for Form SS-4
The business name has to match too. Use the legal name you registered on the SS-4. If you provided a trade name on that application and chose to file under it, use that trade name consistently across every return. Mixing names between filings triggers automated flags that hold up processing.3Internal Revenue Service. Instructions for Form SS-4 Download forms from IRS.gov so you’re working with current versions.
Which Federal Filings Carry Your EIN
Your EIN ties every piece of your entity’s federal activity to a single IRS account. It appears on income tax returns, employment tax returns, and information returns.
Income Tax Returns
C corporations report income, deductions, and credits on Form 1120 and pay federal tax at the entity level.4Internal Revenue Service. Instructions for Form 1120 (2025) S corporations file Form 1120-S, which generally passes income, losses, and deductions through to shareholders.5Internal Revenue Service. Instructions for Form 1120-S – Purpose of Form Partnerships file Form 1065 as an information return; the EIN on that form is what links each partner’s Schedule K-1 back to the entity.6Internal Revenue Service. About Form 1065, U.S. Return of Partnership Income
Employment Tax Returns
If your business has employees, file employment tax returns under the same EIN you use on the income tax return. Form 941 reports quarterly withholding and Social Security and Medicare taxes.7Internal Revenue Service. Instructions for Form 941 – Who Must File Form 941 Form 940 is the annual return for Federal Unemployment Tax, separate from state unemployment filings.8Internal Revenue Service. About Form 940, Employer’s Annual Federal Unemployment (FUTA) Tax Return An EIN error on either form creates a mismatch between what you reported withholding and what employees claim on their personal returns.
Information Returns
Information returns document what your business paid to others, and your EIN appears on every copy so the recipient can trace the income back to you. Issue Form 1099-NEC to any independent contractor you paid $600 or more for services during the year.9Internal Revenue Service. Instructions for Forms 1099-MISC and 1099-NEC Send Form W-2 to each employee summarizing annual wages and withholding.10Internal Revenue Service. About Form W-2, Wage and Tax Statement If you file 10 or more information returns in a year, including W-2s filed with the Social Security Administration, you must file them electronically.11Internal Revenue Service. E-File Information Returns
Standard Deadlines for Calendar-Year Filers
Deadlines matter because a wrong EIN plus a late return compounds the problem. For calendar-year filers:12Internal Revenue Service. Publication 509 (2026), Tax Calendars
- Form 1065 (partnerships): March 15, with a six-month extension available on Form 7004.
- Form 1120-S (S corporations): March 15, with the same six-month extension on Form 7004.
- Form 1120 (C corporations): April 15, with a six-month extension on Form 7004.
- Form 941 (quarterly employment taxes): April 30, July 31, October 31, and January 31. Timely deposits earn an extra 10 calendar days after the quarterly deadline to file.13Internal Revenue Service. Employment Tax Due Dates
- Forms W-2 and 1099-NEC: January 31, for both recipient copies and the IRS copies.9Internal Revenue Service. Instructions for Forms 1099-MISC and 1099-NEC
Fiscal-year filers use the same logic counted from the end of their tax year. An extension gives you more time to file, but not more time to pay.
What EIN and Filing Errors Cost
Penalties for incorrect or late information returns scale with how long you take to fix them. For returns required to be filed in 2026, the penalty starts at $60 per return if corrected within 30 days of the due date, rises to $130 per return if corrected by August 1, and reaches $340 per return after that. Intentional disregard runs $680 per return with no annual cap, and the tiered penalties carry their own annual maximums that are lower for small businesses with gross receipts of $5 million or less.14Internal Revenue Service. Rev. Proc. 2024-40 These amounts apply per return, so a business with 50 incorrect 1099-NECs left unfixed past August 1 would face $17,000 in penalties before the IRS looks at the underlying tax numbers.
Late partnership and S corporation returns carry their own hit: $255 per partner or shareholder for each month or partial month late, up to 12 months.15Internal Revenue Service. Failure to File Penalty A four-partner LLC that files Form 1065 three months late owes $3,060. The penalty applies even if the partnership owes no tax, because the return is an information filing the IRS uses to verify what partners report on their own returns.
Keeping the EIN Account Accurate
Your EIN stays with the entity permanently, but the information tied to it has to stay current. When your business changes its responsible party (the person who controls, manages, or directs the entity), you must file Form 8822-B within 60 days. The requirement is mandatory.16Internal Revenue Service. Form 8822-B, Change of Address or Responsible Party – Business
Form 8822-B also covers changes to your business mailing address or physical location. Mail it separately to the IRS address on the form rather than attaching it to a return. Processing typically takes four to six weeks. If the responsible party or address on file is stale, you may never receive notices of deficiency or demands for payment, and penalties and interest keep accruing while you’re unaware.16Internal Revenue Service. Form 8822-B, Change of Address or Responsible Party – Business
Finding an EIN You’ve Lost
Before calling the IRS, work through the places the number is likely already recorded:2Internal Revenue Service. Employer Identification Number
- The original IRS assignment notice (Notice CP 575) or your SS-4 confirmation.
- The bank where your business account is held.
- State or local license applications where you provided the number.
- A previously filed business tax return.
If those don’t turn it up, call the IRS Business and Specialty Tax Line at 800-829-4933, Monday through Friday, 7 a.m. to 7 p.m. local time. The IRS will verify your identity and confirm you’re authorized to receive the number before releasing it.2Internal Revenue Service. Employer Identification Number
Closing an EIN Account
The IRS cannot cancel an EIN outright; once assigned, the number permanently belongs to the entity. What you can do is ask the IRS to deactivate the account. First file all outstanding returns and pay any tax owed. Then send a letter that includes the EIN, the entity’s legal name, its address, the reason for deactivating, and the original EIN assignment notice if you have it. Mail the letter to Internal Revenue Service, MS 6055, Kansas City, MO 64108, or Internal Revenue Service, MS 6273, Ogden, UT 84201.17Internal Revenue Service. If You No Longer Need Your EIN
Tax-exempt organizations follow a different track. An organization that has applied for exemption, been covered in a group ruling, or filed an information return cannot simply deactivate its EIN. Exempt organizations that do qualify should send the deactivation letter to the Ogden address (Attn: EO Entity, Mail Stop 6273) or fax it to 855-214-7520.17Internal Revenue Service. If You No Longer Need Your EIN