Missing a tax deadline costs money — penalties, interest, and stress. Here is every federal and Indiana state tax deadline small business owners need to know for 2025, organized by month.
Missing a tax deadline is one of the most avoidable ways to lose money in business. The IRS and Indiana Department of Revenue charge penalties and interest on late filings and late payments — and those charges add up quickly. A single missed quarterly estimated payment can result in an underpayment penalty even if you pay everything you owe by April 15.
This calendar covers the key federal and Indiana state tax deadlines for 2025 that apply to most small business owners. Bookmark it, add the dates to your calendar, and review it with your CPA at the start of each quarter.
Note: Deadlines that fall on a weekend or federal holiday shift to the next business day. Dates below reflect the standard schedule; confirm with your CPA if a deadline shifts in a given year.
January 2025
January 15 — Q4 2024 Estimated Tax Payment Due Federal Form 1040-ES and Indiana Form ES-40. This covers income earned September–December 2024. If you file your 2024 return and pay any balance due by January 31, you can skip this payment.
January 31 — W-2s and 1099s Must Be Issued If you have employees, W-2s must be postmarked or electronically delivered to employees by January 31. If you paid any contractor $600 or more in 2024, Form 1099-NEC must be issued to the contractor and filed with the IRS by January 31.
January 31 — Q4 2024 Payroll Tax Return (Form 941) Federal quarterly payroll tax return for October–December 2024.
January 31 — Indiana WH-3 Annual Reconciliation Indiana employers must file the annual withholding reconciliation with the Indiana DOR.
February 2025
February 28 — Paper 1099 Filing with IRS If you are filing 1099-NEC or 1099-MISC on paper (not electronically), the IRS copy is due February 28. Electronic filers have until March 31.
March 2025
March 15 — S-Corporation and Partnership Returns Due (Form 1120-S / Form 1065) S-Corps file Form 1120-S and Indiana Form IT-20S. Partnerships file Form 1065 and Indiana Form IT-65. These are pass-through entities — the return itself is due March 15, even though the owners' personal returns are due April 15.
March 15 — S-Corp Election Deadline for 2025 If you want your LLC to be taxed as an S-Corporation starting in 2025, Form 2553 must be filed by March 15.
March 31 — Electronic 1099 Filing with IRS Electronic 1099-NEC and 1099-MISC filings are due to the IRS by March 31.
April 2025
April 15 — Individual and C-Corporation Tax Returns Due
- Form 1040 (individual/sole proprietor) and Indiana Form IT-40
- Form 1120 (C-Corporation) and Indiana Form IT-20
- FBAR (FinCEN Form 114) for foreign financial accounts over $10,000
April 15 — Q1 2025 Estimated Tax Payment Due Federal Form 1040-ES and Indiana Form ES-40. Covers income earned January–March 2025.
April 15 — IRA and HSA Contribution Deadline Last day to make 2024 IRA contributions (Traditional and Roth) and 2024 HSA contributions.
April 30 — Q1 2025 Payroll Tax Return (Form 941) Federal quarterly payroll tax return for January–March 2025.
May 2025
No major small business tax deadlines in May for most entities. Use this month to review Q1 financials and project Q2 estimated taxes.
June 2025
June 16 — Q2 2025 Estimated Tax Payment Due Federal Form 1040-ES and Indiana Form ES-40. Covers income earned April–May 2025. Note: Q2 only covers two months, not three.
July 2025
July 31 — Q2 2025 Payroll Tax Return (Form 941) Federal quarterly payroll tax return for April–June 2025.
August 2025
No major small business tax deadlines in August for most entities.
September 2025
September 15 — Q3 2025 Estimated Tax Payment Due Federal Form 1040-ES and Indiana Form ES-40. Covers income earned June–August 2025.
September 15 — Extended S-Corporation and Partnership Returns Due If you filed for an extension in March, your extended S-Corp (Form 1120-S) and partnership (Form 1065) returns are due September 15.
October 2025
October 15 — Extended Individual and C-Corporation Returns Due If you filed for an extension in April, your extended Form 1040 and Form 1120 are due October 15. Note: an extension gives you more time to file, not more time to pay. Any tax owed was still due April 15.
October 31 — Q3 2025 Payroll Tax Return (Form 941) Federal quarterly payroll tax return for July–September 2025.
November 2025
No major small business tax deadlines in November. Use this month for year-end tax planning — review your projected income, consider accelerating deductions, and evaluate retirement contributions.
December 2025
December 31 — Year-End Tax Planning Deadline Many tax strategies must be executed by December 31 to apply to the 2025 tax year:
- Solo 401(k) contributions (the plan must be established by December 31 for new plans)
- Bonus depreciation and Section 179 asset purchases
- Charitable contributions
- Business expense timing decisions
Indiana-Specific Deadlines to Know
Indiana WH-1 (Withholding Tax) — Indiana employers file monthly or quarterly depending on withholding volume. Monthly filers are due by the 30th of the following month. Quarterly filers follow the same schedule as federal Form 941.
Indiana URT-1 (Unemployment Insurance) — Indiana unemployment tax returns are due quarterly: April 30, July 31, October 31, and January 31.
Indiana BIT-20 (Business Income Tax) — Applies to certain pass-through entities with non-resident shareholders. Due with the entity return.
A Note on Extensions
Filing an extension is not a penalty — it is a tool. If you need more time to gather documents or your return is complex, file for an extension. But remember: an extension extends the filing deadline, not the payment deadline. If you owe taxes, you must estimate and pay by the original due date to avoid penalties and interest.
Stay Ahead of Deadlines
The best way to avoid deadline stress is to work with a CPA who tracks these dates for you and reaches out proactively. I send reminders to my clients before each major deadline and help them plan estimated payments based on actual year-to-date income — not guesswork.
Want a CPA who keeps you ahead of the calendar? Schedule a consultation — I work with small businesses across Northwest Indiana and remotely nationwide.
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Written by
Kristine Conley, CPA
Licensed CPA serving small businesses and individuals in Northwest Indiana and remotely nationwide. Specializing in tax preparation, bookkeeping, and proactive tax planning for startups and growing businesses.
