S Corp Tax Extension: Form 7004 for Form 1120-S
Quick answer
An S corporation extends Form 1120-S with Form 7004, code 25. For calendar-year 2026, file it by March 15, 2027. The return is then due September 15, 2027.
The extension covers filing only. Any tax the S corporation owes is still due March 15, 2027.
- Form code
- 25
- File Form 7004 by
- March 15, 2027
- Extended due date
- September 15, 2027
- Extension
- 6 months
Who this covers
Any corporation that files Form 1120-S, including an LLC that elected to be taxed as an S corporation. The shareholders' own returns are separate: an individual shareholder who needs more time uses Form 4868.
How to file an S corp extension online
Fill it out online free here, print it and mail it by March 15, 2027. Or e-file it through an authorized e-file provider, which has a cost and gets you an IRS acknowledgment. Either way, enter code 25 on line 1.
Does an S corporation owe tax on line 6?
Usually not much, if anything. An S corporation generally passes income through to its shareholders. But it can owe tax itself in some cases, such as the tax on built-in gains or the excess net passive income tax. Use the Form 1120-S instructions to estimate it, and enter -0- on line 6 if you expect none.
The S corp late-filing penalty is per shareholder
If Form 1120-S is filed after its due date, including extensions, the penalty applies even when no tax is due. It's $255 for each month or part of a month late, up to 12 months, times the number of shareholders during the year. That's the amount for returns required to be filed in 2026.
Example: three shareholders, two months late, no tax due: $255 x 3 x 2 = $1,530. If tax is due, add 5% of the unpaid tax for each month late, up to 25%. Separate penalties can apply for each Schedule K-1 not furnished to a shareholder on time. The IRS can waive penalties for reasonable cause.
That's the real reason to extend if you can't finish on time: a filed Form 7004 moves the penalty clock to September 15, 2027.
Shareholders and their K-1s
Extending Form 1120-S also pushes back when shareholders get their Schedule K-1s, so they may need to extend their own returns. Individual shareholders use Form 4868, which extends Form 1040 to October 15.
Where to file an S corp Form 7004
| Principal business, office or agency | Total assets at year end | Mail to |
|---|---|---|
| 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, Wisconsin | Less than $10 million | Department of the Treasury Internal Revenue Service Kansas City, MO 64999-0019 |
| Same states as above | $10 million or more | Department of the Treasury Internal Revenue Service Ogden, UT 84201-0045 |
| Every other state | Any amount | Department of the Treasury Internal Revenue Service Ogden, UT 84201-0045 |
| A foreign country or U.S. territory | Any amount | Internal Revenue Service P.O. Box 409101 Ogden, UT 84409 |
Not sure? Look up your address by return, state and assets.
Fiscal-year S corporations
Form 1120-S is due on the 15th day of the 3rd month after the tax year ends, and the extension is 6 months. Calculate your dates.
Common S corp extension mistakes
- Code 12 instead of 25. 12 is Form 1120, for C corporations.
- Assuming April 15. Calendar-year S corporations are due in March.
- Using a new name that doesn't match last year's return.
- Forgetting the shareholders. Their extensions are separate.
Last reviewed: · Based on 4 IRS sources
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