2026 Tax Deadlines Every Cincinnati Filer Should Know
The dates that matter for individuals, S-Corps and partnerships — plus the local ones the IRS calendar leaves out.
Every year we watch smart Cincinnati filers get burned by the same handful of dates. The federal calendar gets most of the attention, but Ohio, Kentucky and the local municipal returns run on their own clocks — and they all move around when a due date lands on a weekend or holiday. Here's the plain-English version of what to put on your 2026 calendar right now.
The federal dates that matter most
- January 15, 2026 — Q4 2025 estimated tax payment due for individuals, freelancers and sole proprietors.
- January 31, 2026 — W-2s to employees and 1099-NECs to contractors. Miss this one and the IRS penalties compound quickly.
- March 16, 2026 — S-Corp (1120-S) and partnership (1065) returns due, or file an extension. This is not April.
- April 15, 2026 — Individual 1040, C-Corp 1120, IRA/HSA contributions, and Q1 2026 estimated payments.
- June 15, 2026 — Q2 2026 estimates due, plus the automatic deadline for U.S. citizens living abroad.
- September 15, 2026 — Extended S-Corp and partnership returns due; Q3 2026 estimates.
- October 15, 2026 — Extended individual 1040 returns due.
- January 15, 2027 — Q4 2026 estimated payments.
The Ohio, Kentucky and municipal dates people forget
If you live or work in Greater Cincinnati, you're almost certainly filing more than a federal return. Ohio's individual return (IT 1040) and Kentucky's 740 both track the April 15 federal deadline, but city and school district returns are the real trap.
- Cincinnati and most Hamilton/Clermont County municipal returns are due April 15, 2026 — the RITA and CCA filings included.
- Ohio School District Income Tax (SD 100) is due April 15, 2026 if your district levies it. Milford, Batavia and West Clermont districts all do.
- Kentucky occupational license returns for Boone, Kenton and Campbell counties have their own due dates — usually April 15, but the forms vary by city.
- Ohio CAT (Commercial Activity Tax) quarterly filers: May 10, August 10, November 10, and February 10 for the prior quarter.
An extension is not a payment plan
The single biggest misconception we correct every April: filing an extension only pushes back the paperwork, not the money. If you owe, you owe on April 15. Pay a reasonable estimate with the extension request and you'll avoid the 0.5%-per-month late-payment penalty — even if the return itself doesn't get filed until October.
How we help clients stay ahead
Every January we send our clients a personalized deadline calendar — federal, Ohio, Kentucky, city, and estimated payments — so nothing sneaks up on them. If you'd like one, schedule a free consultation and we'll build yours in the first meeting.
