A calendar-year S corporation filing its 2025 federal return was generally required to file Form 1120-S by March 16, 2026 because March 15 fell on a Sunday. A timely, valid Form 7004 generally extends the filing deadline to September 15, 2026. The filing extension does not automatically extend payroll filings, shareholder returns, estimated payments, or the time to pay tax that may be due.
What is the 2026 Form 1120-S deadline?
For an ordinary calendar-year S corporation filing its 2025 return, the federal Form 1120-S deadline was Monday, March 16, 2026. A timely, valid Form 7004 generally provides a six-month filing extension to September 15, 2026.
The date is tied to the corporation’s tax year. Fiscal years, short years, final returns, a terminated S election, and other special circumstances can produce a different filing date.
Form 1120-S and Form 2553 have different jobs
Form 1120-S is the annual S corporation income-tax return. Form 2553 is the election used by an eligible entity to request S corporation treatment. Extending Form 1120-S does not extend the separate deadline for making an S election.
Before filing Form 1120-S, confirm that the IRS accepted the S election and that it remained effective for the year. A late or uncertain election may require a separate review rather than simply changing the return title.
When are shareholder K-1s due?
An S corporation generally furnishes Schedule K-1, and Schedule K-3 when applicable, by the date Form 1120-S is required to be filed, including a valid extension. Shareholders use the K-1 to report their shares of S corporation items on their personal returns.
The corporation’s extension does not automatically extend a shareholder’s Form 1040 or state return. A delayed K-1 should be coordinated with the shareholder’s filing status, estimates, basis records, and any return already filed.
An extension does not cover payroll or every payment
Form 7004 generally extends time to file the S corporation return when filed properly and on time. It does not automatically extend payroll deposits, Forms 941 or 940, Forms W-2, shareholder estimated payments, state obligations, or the time to pay any entity-level tax that may apply.
Officer compensation, payroll reporting, shareholder health insurance, distributions, and basis records should be reconciled with the return rather than treated as unrelated year-end items.
What if the S corporation missed March 16?
First confirm whether Form 1120-S or Form 7004 was electronically accepted, mailed on time, or covered by a specific relief notice. Do not assume that filing an extension after the original deadline makes it timely.
If no valid extension applies, gather the books, payroll records, ownership information, and prior filings promptly. Late-filing and late-payment consequences depend on the corporation’s facts, tax due, shareholders, timing, and available relief.
State and disaster-relief dates require a separate check
Federal S corporation status, filing extensions, and payment rules do not create one uniform state result. States can require separate elections, returns, extensions, franchise taxes, pass-through entity taxes, or payments.
A specific IRS disaster-relief notice may postpone certain deadlines for eligible affected taxpayers. Confirm the covered location, form, taxpayer, and period, and separately review state relief.
Records to gather for an extended or late Form 1120-S
- The prior Form 1120-S, state returns, S-election confirmation, and extension acceptance
- Tax-ready financial statements, general ledger, and year-end reconciliations
- Shareholder ownership, contributions, distributions, stock basis, and debt basis information
- Payroll reports, officer compensation, Forms W-2, and shareholder health-insurance records
- Fixed assets, depreciation, estimated payments, loans, and major transactions
- State activity and any Schedule K-1 or K-3 reporting needs