With 2026 winding down, it is worth getting the full 2027 tax calendar on your radar now, rather than discovering each deadline as it arrives. Here are the dates that matter most for Ohio business owners and individual filers, in order.

January 15, 2027

Fourth quarter 2026 estimated tax payment due for individuals and pass-through entity owners.

January 31, 2027 (bumped to Monday, February 1, since January 31 falls on a Sunday)

W-2s due to employees and 1099-NEC forms due to contractors paid $600 or more in 2026.

March 15, 2027

Filing deadline for partnerships, Form 1065, and S corporations, Form 1120-S, on a calendar year. This is also generally the deadline to file Form 2553 for an S corp election to take effect for the 2027 tax year.

April 15, 2027

Individual returns, Form 1040, and C corporation returns, Form 1120, due for the 2026 tax year, or file for an automatic extension. This is also the deadline for the first 2027 quarterly estimated tax payment, and the last day to make 2026 IRA contributions.

June 15, 2027

Second quarter 2027 estimated tax payment due.

September 15, 2027

Third quarter 2027 estimated tax payment due. Extended deadline for partnerships and S corporations that filed for a six month extension in March. This is also when K-1s from those entities finally go out, which can create a scramble for individual owners waiting on them.

October 15, 2027

Extended deadline for individual and C corporation returns that filed for an automatic extension in April.

Looking just past year end

The fourth quarter 2027 estimated payment falls on January 18, 2028, shifted from January 15, a Saturday. Worth noting now if you are setting up automatic reminders for the year.

Practical takeaway

The dates that trip owners up most are the ones that do not match the calendar quarter intuition, like the March 15 pass-through deadline a full month before the April 15 date most people expect, and the January estimated payment that lands after the year it covers has already ended. Put all of these on a shared calendar now, not as each one approaches.

Sources and further reading

●       IRS Publication 509, Tax Calendars

●       IRS Form 1040-ES, Estimated Tax for Individuals

If any of these dates intersect with a decision you have been putting off, an entity election or an owner compensation change, let's talk before the deadline is on top of you. Call our office at 216-644-3359, or contact us online to share the details of your situation.