April 15 | Individual Income Tax Returns Due (Form 1040)

April 15 | First 2025 Estimated Tax Payment Due

April 15 | C Corporation Tax Return Due (Form 1120), if calendar year

April 15 | Deadline to contribute to IRA and HSA for 2024

April 15 | Form 4868 for Individual Extension Due

June 16 | Q2 2025 Estimated Tax Payment Due

September 15 | Extended deadline for S Corp & Partnership returns (1120S, 1065)

September 15 | Q3 2025 Estimated Tax Payment Due

October 15 | Extended Individual Income Tax Return Due (Form 1040)

October 15 | Extended C Corporation Return Due (Form 1120)

December 31 | Last day to make many tax-deductible business purchases for the year

December 31 | Deadline for year-end planning (bonuses, 401k contributions, tax deferrals)