If you’re wondering where to file Form 1120, the short answer is that most C-corporations no longer mail it anywhere: the IRS requires electronic filing for any corporation that files 10 or more returns of any type during the calendar year.1eCFR. 26 CFR 301.6011-5 – Required Use of Electronic Form for Corporate Income Tax Returns Corporations that legitimately paper file send the return to one of two IRS service centers, Kansas City, Missouri or Ogden, Utah, based on the state of the principal office and total assets at year-end.
Who Can Still Paper File
The 10-return count includes income tax returns, employment tax returns, excise tax returns, and information returns like W-2s and 1099s, all added together.2Internal Revenue Service. Instructions for Form 1120 (2025) Because most corporations file at least a handful of W-2s and 1099s alongside the income tax return, the threshold sweeps in nearly everyone. Controlled groups aggregate their return counts across all members, so a small subsidiary can be pulled into mandatory e-filing by the group’s total.1eCFR. 26 CFR 301.6011-5 – Required Use of Electronic Form for Corporate Income Tax Returns
A corporation that meets the threshold but faces real obstacles can request a waiver on Form 8508. Valid grounds include undue financial hardship (the cost of e-filing exceeds the cost of paper filing), a federally declared disaster that disrupted operations, or being a first-year business. First-time waiver requests are automatically granted. Corporations whose religious beliefs conflict with the required technology are permanently exempt but should still file Form 8508 once to notify the IRS.
Everything below assumes you’re in that smaller group actually mailing a return. Confirm addresses against the current year’s Form 1120 instructions before you send it, because the IRS periodically reassigns states between processing centers.3Internal Revenue Service. Where to File Your Taxes (for Forms 1120)
Mailing Address for Kansas City Filers
Send Form 1120 to Kansas City if your principal business, office, or agency is in one of the states listed below, your total assets at the end of the tax year are less than $10 million, and you are not filing Schedule M-3.
Department of the Treasury
Internal Revenue Service
Kansas City, MO 64999-0012
The states in this group are Connecticut, Delaware, District of Columbia, Georgia, Illinois, Indiana, Kentucky, Maine, Maryland, Massachusetts, Michigan, New Hampshire, New Jersey, New York, North Carolina, Ohio, Pennsylvania, Rhode Island, South Carolina, Tennessee, Vermont, Virginia, West Virginia, and Wisconsin.3Internal Revenue Service. Where to File Your Taxes (for Forms 1120)
Miss any of the three conditions and the return goes to Ogden instead.
Mailing Address for Ogden Filers
Send Form 1120 to Ogden if any of the following is true: your principal office is in one of the states listed above but your total assets are $10 million or more, you are filing Schedule M-3 regardless of asset size, or your principal office is in any state not on the Kansas City list.2Internal Revenue Service. Instructions for Form 1120 (2025)
Department of the Treasury
Internal Revenue Service
Ogden, UT 84201-0012
The all-Ogden states are Alabama, Alaska, Arizona, Arkansas, California, Colorado, Florida, Hawaii, Idaho, Iowa, Kansas, Louisiana, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Mexico, North Dakota, Oklahoma, Oregon, South Dakota, Texas, Utah, Washington, and Wyoming.3Internal Revenue Service. Where to File Your Taxes (for Forms 1120)
Enclosing a check with the return doesn’t change the address. Make it payable to “U.S. Treasury” and write the corporation’s name, address, Employer Identification Number, the tax year, and “Form 1120” on the payment itself.4Internal Revenue Service. Pay by Check or Money Order
Street Addresses for FedEx, UPS, and DHL
Regular USPS mail can go to the P.O. box addresses above, and USPS certified or registered mail qualifies for the “timely mailing treated as timely filing” rule, meaning the postmark date counts as the filing date.5Office of the Law Revision Counsel. 26 USC 7502 – Timely Mailing Treated as Timely Filing and Paying Private carriers can’t deliver to P.O. boxes, so if you use FedEx, UPS, or DHL you need the physical street address of the processing center:6Internal Revenue Service. Submission Processing Center Street Addresses for Private Delivery Service (PDS)
- Kansas City: Internal Revenue Submission Processing Center, 333 W. Pershing, Kansas City, MO 64108
- Ogden: Internal Revenue Submission Processing Center, 1973 Rulon White Blvd., Ogden, UT 84201
The timely-mailing rule only protects you if you use one of the IRS-designated private delivery service tiers. Qualifying options include FedEx First Overnight, Priority Overnight, Standard Overnight, 2 Day, International Next Flight Out, International Priority, International First, and International Economy; UPS Next Day Air Early A.M., Next Day Air, Next Day Air Saver, 2nd Day Air, 2nd Day Air A.M., Worldwide Express Plus, and Worldwide Express; and eight DHL Express tiers including DHL Express 9:00, 10:30, 12:00, Worldwide, and Envelope, plus DHL Import Express 10:30, 12:00, and Worldwide.7Internal Revenue Service. Private Delivery Services (PDS) FedEx Ground, UPS Ground, and other economy tiers are not on the list. Ship with one of those and the IRS will not treat the shipping date as the filing date.
Addresses for Related 1120-Series Returns
Not everyone filing something labeled “1120” is filing Form 1120. A few common variants have their own routing.
Form 1120-F for Foreign Corporations
A foreign corporation with U.S. tax obligations files Form 1120-F, not the standard Form 1120. All paper 1120-F returns go to a single address regardless of location or asset size:8Internal Revenue Service. Instructions for Form 1120-F (2025)
Internal Revenue Service Center
P.O. Box 409101
Ogden, UT 84409
Form 1120-RIC for Regulated Investment Companies
Regulated investment companies use the same two-center, state-and-asset-size split as regular Form 1120 filers. Filers with a principal office in the eastern-state group whose total assets are under $10 million and who don’t file Schedule M-3 go to Kansas City; everyone else goes to Ogden.9Internal Revenue Service. Mailing Addresses for Forms 1120-RIC
Form 1120-POL for Political Organizations
Political organizations taxed under Section 527 file Form 1120-POL. Domestic filers mail the return to Ogden, UT 84201. Organizations with a principal office in a foreign country or U.S. territory use the P.O. Box 409101, Ogden, UT 84409 address.10Internal Revenue Service. Instructions for Form 1120-POL (2025)
Form 1120-X for Amended Returns
Correcting a mistake on a previously filed Form 1120 means filing Form 1120-X. Send the amended return to the same IRS service center where the original was filed.11Internal Revenue Service. Instructions for Form 1120-X If you owe additional tax and aren’t paying electronically, enclose a check payable to “United States Treasury” marked with the corporation’s name, EIN, tax year, and “Form 1120-X.”
Filing Deadlines and What Late Filing Costs
A calendar-year C-corporation files Form 1120 by April 15. Fiscal-year corporations file by the 15th day of the fourth month after the year ends, except that a June 30 year-end triggers a September 15 deadline (the 15th day of the third month).12Internal Revenue Service. Instructions for Form 1120 (2025) When the deadline falls on a weekend or legal holiday, filing on the next business day is timely. Form 7004 buys an automatic six-month extension of time to file, but not of time to pay; tax owed is still due by the original deadline.13Internal Revenue Service. Instructions for Form 7004
Missing the filing deadline triggers a failure-to-file penalty of 5 percent of the unpaid tax for each month or partial month the return is late, capped at 25 percent.14Office of the Law Revision Counsel. 26 USC 6651 – Failure to File Tax Return or to Pay Tax If the return is more than 60 days late, the minimum penalty is $525 or 100 percent of the unpaid tax, whichever is less, and that floor applies even when the balance owed is small.15Internal Revenue Service. Failure to File Penalty
A separate failure-to-pay penalty runs at 0.5 percent of unpaid tax per month, also capped at 25 percent.16Internal Revenue Service. Failure to Pay Penalty When both apply in the same month, the filing penalty is reduced by the payment penalty, so the combined monthly charge is 5 percent rather than 5.5 percent. If the IRS issues a notice of intent to levy and the corporation still doesn’t pay within 10 days, the payment penalty rises to 1 percent per month. Either penalty can be waived on a showing of reasonable cause.