United States · tax year 2026
Business tax return due dates, tax year 2026
For tax year 2026, a calendar-year S corporation (Form 1120-S) or partnership (Form 1065) files by March 15, 2027; a C corporation (Form 1120) and a sole proprietor reporting on Schedule C of Form 1040 file by April 15, 2027. A Form 7004 or Form 4868 extension moves the filing date by six months but not the payment date.
At a glance · tax year 2026
- Forms 1120-S and 1065
- March 15, 2027
- Form 1120 and Form 1040
- April 15, 2027
- Form 1120, extended
- October 15, 2027
Written and reviewed by Godwin Pinto, ACA (ICAI) · checked October 1, 2026
| Return | Filed by | Due (tax year 2026) | Extended filing date | Extension form | Source |
|---|---|---|---|---|---|
| Form 1120-S | S corporations | March 15, 2027 | September 15, 2027 | Form 7004 | IRS Instructions for Form 1120-S (2025), When To File |
| Form 1065 | Partnerships | March 15, 2027 | September 15, 2027 | Form 7004 | IRS Instructions for Form 1065 (2025), When To File |
| Form 1120 | C corporations | April 15, 2027 | October 15, 2027 | Form 7004 | IRS Instructions for Form 1120 (2025), When To File; Tax Payments |
| Form 1040 with Schedule C | Individuals, including sole proprietors | April 15, 2027 | October 15, 2027 | Form 4868 | IRS Tax Topic 301, When to file |
Calendar-year filers, tax year 2026. Which return a business files depends on its legal form and any tax elections it has made.
How is each date worked out?
From the IRS rule for each form. Form 1120: “by the 15th day of the 4th month after the end of its tax year.” (IRS Instructions for Form 1120 (2025), When To File; Tax Payments). Form 1120-S: “by the 15 day of the 3rd month after the end of its tax year.” (IRS Instructions for Form 1120-S (2025), When To File). Form 1065: “by the 15th day of the 3rd month following the date its tax year ended” (IRS Instructions for Form 1065 (2025), When To File). A date that lands on a weekend or federal legal holiday moves to the next business day.
Does an extension move the payment date?
No. “The automatic extension period for time to file is generally 6 months. … Form 7004 does not extend the time to pay any tax due.” (IRS Instructions for Form 7004 (12/2025), Extension Period; Payment of Tax). For individuals: “Use Form 4868 to apply for 6 more months … Form 4868 doesn’t extend the time to pay taxes.” (IRS Form 4868 (2025), page 1, Purpose of Form; Qualifying for the Extension).
What does Nella show?
Nella reads your QuickBooks or Xero data and keeps a federal filing calendar for your business. It dates a return once you tell Nella which federal return the business files and confirm its tax year ends December 31; anything it cannot date is listed as a gap, never guessed. Nella does not calculate sales tax, state taxes or the tax itself, and it does not file anything. Nella shows an extended date only once the business confirms an extension was obtained, and labels it as stated.
Nella provides financial information and education, not accounting or tax advice. Facts for tax year 2026, taken from the sources linked on this page. Created by the accountants at AccTek Ltd — an ICPA and AIA member firm.
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