Small business tax deadlines: December 2026 to May 2027 calendar
Founder-led service firms have three tax deadlines in the next 90 days:
December 15, 2026: fourth-quarter estimated tax for C corporations.
January 15, 2027: fourth-quarter estimated tax for owners, sole proprietors, partners, and S-corp shareholders.
February 1, 2027: W-2s and 1099-NEC forms go to workers and the government.
After that, the dates to watch are March 15 for partnerships and S corporations and April 15 for individuals and C corporations.
Key deadlines at a glance
Date | What is due | Applies to |
|---|---|---|
Nov 10, 2026 | Form 941 for Q3 2026, if all deposits were made on time (otherwise it was due Nov 2) | Employers |
Dec 15, 2026 | Fourth-quarter estimated tax payment for 2026 | Calendar-year C corporations |
Dec 31, 2026 | Last day of the tax year. Spending, payroll, and equipment purchases must happen by today to count for 2026 | Calendar-year businesses |
Jan 15, 2027 | Fourth-quarter estimated tax payment for 2026 | Individuals, sole proprietors, partners, and S-corp shareholders |
Feb 1, 2027 | Form W-2 to employees and the Social Security Administration. Form 1099-NEC to contractors and the IRS. Form 1099-MISC to recipients | Employers and businesses that paid contractors |
Feb 1, 2027 | Form 941 for Q4 2026 (or Form 944 if you file annually) and Form 940 for federal unemployment tax. Both move to Feb 10 if all deposits were made on time | Employers |
Mar 1, 2027 | Form 1099-MISC to the IRS if filing on paper (Mar 31 if filing electronically) | Businesses that issued 1099-MISC |
Mar 15, 2027 | Form 1065 and Form 1120-S returns and Schedules K-1, or Form 7004 for a six-month extension | Partnerships, multi-member LLCs, and S corporations |
Mar 15, 2027 | Form 2553 to elect S-corp status for the 2027 tax year | Businesses switching to S-corp taxation |
Apr 15, 2027 | Form 1040 and Form 1120 returns, or extensions (Form 4868 and Form 7004). First estimated tax payment for 2027 | Individuals, sole proprietors, and C corporations |
Apr 30, 2027 | Form 941 for Q1 2027 | Employers |
May 17, 2027 | Form 990 series returns | Calendar-year nonprofits |
Several dates shift because of the IRS weekend rule: when a due date lands on a Saturday, Sunday, or legal holiday, it moves to the next business day. January 31, 2027 falls on a Sunday, so W-2 and 1099-NEC filings are due Monday, February 1. May 15, 2027 falls on a Saturday, so nonprofit returns are due Monday, May 17.
Which dates apply to you
If your firm is a... | Your key dates |
|---|---|
Sole proprietor or single-member LLC | Jan 15, Feb 1 (if you pay contractors or staff), Apr 15 |
Partnership or multi-member LLC | Jan 15 (partners’ estimates), Feb 1, Mar 15, Apr 15 (partners’ personal returns) |
S corporation | Jan 15 (shareholders’ estimates), Feb 1, Mar 15, Apr 15 (shareholders’ personal returns) |
C corporation | Dec 15, Feb 1, Apr 15 |
Nonprofit | Feb 1, May 17 |
Any firm with employees | Nov 10 (if deposits were on time), Feb 1, Apr 30 |
The January 15 deadline most owners miss
January 15 gets missed most often because it lands between the holidays and filing season. The IRS offers a shortcut: individuals who file their full 2026 return and pay the entire balance by February 1, 2027 do not have to make the January 15 estimated payment. It only works if your books are closed early enough for your CPA to prepare the return in January, which is rare for firms that close the year in March.
For a simpler approach to estimated payments, see how safe harbor rules for small taxpayers work.
What happens if you miss a deadline
Late filing and late payment can each trigger penalties, plus interest on unpaid tax. The amount depends on the form, the balance due, and how late you are. Information returns like W-2s and 1099s carry per-form penalties that add up quickly for firms with many contractors.
If a payroll form goes out with errors, there is a set process for correcting payroll tax errors with Form 941-X. Either way, keep a dated record of every filing and payment so your CPA can respond quickly if a notice arrives.
How clean books support every deadline
Deadline type | What your CPA needs | Where it comes from |
|---|---|---|
Estimated payments | A reliable year-to-date profit figure | A month-end close done every month, not at year-end |
W-2s and 1099s | Payroll and contractor totals that match the general ledger | Contractor payments tracked through a 1099 vendor management process |
Business tax returns | A reconciled trial balance for the full year | Twelve clean monthly closes and a year-end compliance checklist |
For the details behind February 1, see our guide to 1099s and W-2s at year-end. If you are weighing the March 15 election, read S-corp election deadlines.
AI-powered. Experts in the Loop. Numetix closes your books every month and keeps payroll and contractor data reconciled, so meeting a deadline is a file pull, not a rebuild. Start with Numetix bookkeeping.
Always consult your CPA for advice specific to your entity type, tax year, and any extensions you may request.
This article is for informational purposes only and does not constitute formal legal or tax advice. Dates are based on IRS due-date rules and are subject to change. Verify against the official IRS tax calendar before relying on them. Always consult a qualified tax professional regarding your specific situation.
Numetix is an AI-first accounting firm. AI runs the bookkeeping, tax, payroll, and reporting workflow. Industry experts handle the judgment, month-end close, review, and advisory. We serve founder-led service firms across law, consulting, IT, healthcare, creative, and nonprofit. Headquartered in California, serving clients nationwide.
Suggested Readings
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When are 2026 business tax returns due for an LLC, S corp and partnership, and what are the extension dates?
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IRS penalties for small businesses: rates and relief
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