A firm's tax calendar is a control, not a reminder list. Every date below drives a staffing decision, a client communication and, for audit and review clients, the point at which the financial statements and the tax provision have to agree. This article sets out the 2026 federal dates in IRS Publication 509 and the related IRS pages, how the weekend rule moved some of them, and what an extension actually extends.
The weekend rule that moved the pass-through dates
When a due date falls on a Saturday, Sunday or legal holiday, a timely filing or payment is made on the next business day. That rule decided several 2026 dates. March 15, 2026 was a Sunday, so calendar-year partnerships and S corporations filing for 2025 had until Monday, March 16, 2026. The IRS instructions for Form 1120-S state the March 16 date for exactly that reason. The same Monday applied to a Form 2553 election that was to take effect for 2026. A Form 2553 filed after that date takes effect for calendar year 2027 unless late-election relief applies.
January 31, 2026 was a Saturday. Publication 509 lists February 2, 2026 for Form W-2 copies to employees for 2025 wages and for the 2025 Form 940. The 1099-NEC deadline is also January 31 in the IRS employment tax calendar, so the same next-business-day rule moved the 2025 Form 1099-NEC to February 2, 2026. For tax year 2026, January 31, 2027 is a Sunday, so Forms W-2 and 1099-NEC are due Monday, February 1, 2027.
Calendar-year business and individual returns
| Return | Original due date | Extended due date | Extension form |
|---|---|---|---|
| Form 1065 (partnership) | March 16, 2026 | September 15, 2026 | Form 7004 |
| Form 1120-S (S corporation) | March 16, 2026 | September 15, 2026 | Form 7004 |
| Form 1120 (C corporation) | April 15, 2026 | October 15, 2026 | Form 7004 |
| Form 1040 (individual) | April 15, 2026 | October 15, 2026 | Form 4868 |
Pass-through returns come first because the owners' returns depend on them. A partner or shareholder cannot finish a Form 1040 until the Schedule K-1 or K-3 arrives. A firm that holds back a pass-through return to September also holds back the owners' extended returns in October, and the capacity plan should show that dependency.
Payroll and information return dates
- Form 941 for 2026: April 30 (first quarter), July 31 (second quarter) and November 2 (third quarter, because October 31, 2026 is a Saturday). The fourth quarter is due February 1, 2027 because January 31, 2027 is a Sunday. If every deposit for the quarter was made on time, the IRS allows ten extra calendar days.
- Form 940: February 2, 2026 for 2025, and February 1, 2027 for 2026. The same ten-day grace applies when all FUTA deposits were timely.
- Form W-2: copies to employees and filing with the Social Security Administration with Form W-3 by January 31, which meant February 2, 2026 for 2025 wages and means February 1, 2027 for 2026 wages.
- Forms 1099-NEC: January 31 to both the IRS and the recipient, which meant February 2, 2026 for 2025 and means February 1, 2027 for 2026.
Filing mechanics, penalty tiers and the electronic filing threshold are covered in W-2 and 1099 filing deadlines and penalties. Deposit schedules are in payroll tax deposits: monthly and semiweekly.
Estimated tax dates
Individuals with estimated tax obligations pay on April 15, June 15 and September 15, 2026, and January 15, 2027. The IRS states that individuals generally owe estimated tax when they expect to owe $1,000 or more when the return is filed, and corporations when they expect to owe $500 or more. The safe-harbor rules are in estimated tax payments and safe harbors.
What an extension does and does not do
Form 7004 gives an automatic six-month extension of time to file for the business returns it covers. Form 4868 gives individuals until October 15 to file. Both extend the time to file only. The IRS says plainly that any tax owed on an individual return must be paid by the April filing date, and the extension "is only for filing your return." A corporation must still pay the tax it expects to owe by the original due date, and partnerships carry no income tax at the entity level, so the practical exposure falls on the owners.
Individuals who live outside the United States on the regular due date may get an automatic two-month extension, and a disaster declaration can move dates further. A firm that handles clients in affected areas should record the relief date and the authority for it in the workpapers.
Building the firm calendar
- Load every client against its own year end. The dates above assume calendar-year filers. Fiscal-year entities have their own deadlines, and a short-year return has its own too.
- Set internal dates ahead of statutory ones. A common structure is a document cutoff date, a preparation complete date, a review date and a client signature date. Each should be dated in the engagement tracker.
- Decide extensions early. Deciding on an extension on the day before the deadline compresses the client conversation and invites errors in the safe-harbor estimate. Decide by the document cutoff, then send the Form 7004 or 4868 in time to receive the e-file acknowledgment.
- Track payment separately from filing. For each extended client, record the estimated balance due and who is responsible for confirming it was paid.
- Tie the tax calendar to the audit calendar. Where the firm audits or reviews a client and prepares its return, the provision and the extended return timeline should be planned together. See managing busy season in a small CPA firm.
Common calendar failures
- Treating the extended date as the working deadline, which pushes the whole book of business into the same two weeks.
- Missing the Form 2553 date for a client that formed late in 2025.
- Confusing the 941 extended dates with an extension of time to deposit. The ten-day relief for 941 returns applies only when deposits were timely.
- Assuming an extension of time to file the return extends the time to pay the tax.
FAQ
Is Form 7004 required for each return?
Yes. The form requests an automatic six-month extension of time to file a specific business return, so each entity return needs its own request.
Does a filing extension stop interest?
No. The extension covers filing. Tax owed remains due on the original date.
When is the Form 941 for the fourth quarter of 2026 due?
February 1, 2027, because January 31, 2027 is a Sunday. Timely deposits give ten additional calendar days.
CORAA prepares ready-to-review audit files for US CPA firms; see /us.
Sources
- IRS, Publication 509 (2026), Tax Calendars: https://www.irs.gov/publications/p509
- IRS, Employment tax due dates: https://www.irs.gov/businesses/small-businesses-self-employed/employment-tax-due-dates
- IRS, About Form 7004: https://www.irs.gov/forms-pubs/about-form-7004
- IRS, Extension of time to file your tax return: https://www.irs.gov/filing/extension-of-time-to-file-your-tax-return
- IRS, Estimated taxes: https://www.irs.gov/businesses/small-businesses-self-employed/estimated-taxes
- IRS, Instructions for Form 1120-S: https://www.irs.gov/instructions/i1120s
Part of CORAA University · Tax and compliance for CPA firms: related guides, calculators and templates.
AU-C references are to AICPA Professional Standards, paraphrased here; read the standard itself before relying on a requirement. This page is guidance, not professional advice. Report an error