Small Business Tax Calendar 2025: Every Deadline for Estimated Taxes, Payroll, and Filing
Missing a tax deadline costs money. Late filing penalties, late payment penalties, and estimated tax underpayment penalties are all avoidable with a calendar system that tracks every due date. This guide covers the complete 2025 tax calendar for small business owners, organized by quarter.
2025 Small Business Tax Calendar:
January 2025:
- Jan 15: Q4 2024 estimated tax payment (Form 1040-ES)
- Jan 31: File Form 941 (Q4 2024 payroll tax return)
- Jan 31: Issue W-2s to employees and 1099-NECs to contractors
- Jan 31: File Forms W-2 and W-3 with SSA
- Jan 31: File Form 1099-NEC with IRS (paper or electronic)
February 2025:
- Feb 28: File Form 1099-MISC with IRS (paper; March 31 if electronic)
March 2025:
- Mar 15: S-Corp (1120-S) and partnership (1065) income tax returns due (or extension)
- Mar 15: Issue K-1s to shareholders/partners
- Mar 15: File Form 2553 (S-Corp election) for 2025 calendar year
- Mar 31: File 1099-MISC electronically
April 2025:
- Apr 15: Individual income tax return (1040) due (or extension)
- Apr 15: C-Corp income tax return (1120) due (or extension)
- Apr 15: Q1 2025 estimated tax payment
- Apr 15: Last day to contribute to SEP IRA, Solo 401(k), or traditional IRA for 2024 (without extension)
- Apr 30: File Form 941 (Q1 2025 payroll tax return)
June 2025:
- Jun 16: Q2 2025 estimated tax payment (15th falls on Sunday)
July 2025:
- Jul 31: File Form 941 (Q2 2025 payroll tax return)
September 2025:
- Sep 15: Q3 2025 estimated tax payment
- Sep 15: Extended S-Corp (1120-S) and partnership (1065) returns due
October 2025:
- Oct 15: Extended individual (1040) and C-Corp (1120) returns due
- Oct 15: Last day to contribute to SEP IRA for 2024 (if extension filed)
- Oct 15: Last day to recharacterize a Roth conversion made in 2024 (eliminated by TCJA, included here because the question still arises)
- Oct 31: File Form 941 (Q3 2025 payroll tax return)
December 2025:
- Dec 31: Last day for Solo 401(k) employee deferral for 2025
- Dec 31: Last day for Roth IRA conversion for 2025
- Dec 31: Year-end tax planning deadline (Section 179 purchases, retirement contributions, charitable gifts)
January 2026:
- Jan 15: Q4 2025 estimated tax payment
- Jan 31: File Form 941 (Q4 2025 payroll tax return)
- Jan 31: Issue 2025 W-2s and 1099-NECs
What happens if I miss a tax deadline?
The penalty depends on whether you missed a filing deadline or a payment deadline. Late filing penalties are steeper: 5% of unpaid tax per month, up to 25%. Late payment penalties are 0.5% per month, also capped at 25%. For estimated tax payments, the IRS charges an underpayment penalty at roughly 8% annually on the shortfall for each quarter. Filing an extension avoids the late filing penalty but does NOT extend the payment deadline. If you owe tax, the payment is still due on the original due date (April 15 for individuals, March 15 for S-Corps and partnerships). The most common surprise: March 15 applies to S-Corps and partnerships, not April 15, and no extension is granted for quarterly estimated payments.
Can I get an extension for estimated tax payments?
No. Unlike income tax returns, there is no extension available for estimated tax payments. The four quarterly due dates (April 15, June 15, September 15, January 15) are fixed. If you miss one, the underpayment penalty accrues from that due date until the tax is paid or the filing deadline, whichever comes first. A Form 4868 filing extension (for the annual return) gives you until October 15 to file but does NOT defer the April 15 payment. The distinction matters: many business owners file an extension and assume they can also defer their Q1 estimated payment. They cannot.
Which deadlines are most commonly missed?
The most commonly missed deadlines are the March 15 S-Corp/partnership returns (business owners think April 15 applies to all returns), the quarterly estimated payments (June 15, not June 30, and the Q3 payment is September 15, not September 30), and the January 31 1099-NEC deadline (which was previously March 31 under the old 1099-MISC rules).
Do I need to make estimated tax payments in my first year of business?
Not necessarily. The safe harbor exception under IRC 6654(d)(1)(B) says you owe no underpayment penalty if your total payments (withholding plus estimates) equal or exceed 100% of LAST year’s tax liability (110% if your AGI exceeded $150,000). If you were a W-2 employee last year with modest tax liability, meeting the prior-year safe harbor may be easy even with zero estimated payments. However, if you had no tax liability last year (perhaps you were a student or not working), the prior-year safe harbor is $0 and offers no help. In that case, you should start making estimated payments by the quarter following your first substantial net income.
Related guides:
-
2025 Small Business Tax Calendar: Every Federal Deadline You Need to Know
-
Small Business Tax Calendar: Every Federal Deadline for Sole Proprietors, S-Corps, and Partnerships
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Yarik Yarosh, CPA. "Small Business Tax Calendar 2025: Every Deadline for Estimated Taxes, Payroll, and Filing." Blue Cloud CPA, September 5, 2026. https://bluecloudcpa.com/guides/small-business-quarterly-tax-calendar
This guide is general information, not tax advice for your specific situation. Which points apply, and how, depends on your facts.