March 15 (Extensions Until Sept. 15)Form 1065, U.S. Return of Partnership Income; and
Form 1120S, U.S. Income Tax Return for an S Corporation.
Note: This is the due date for the tax return and also for the Schedules K-1 that the entity must provide to its owners.
April 15 (Extensions Until Oct. 15, Unless Noted Below)Form 1040, U.S. Individual Income Tax Return;
Form 1041, U.S. Income Tax Return for Estates and Trusts (extensions until Sept. 30);
Form 1120, U.S. Corporation Income Tax Return (extensions until Sept. 15)
Note: Calendar-year C corporations can get extensions until Sept. 15 until tax years beginning after 2025, when the extended due date will be Oct. 15. June 30 fiscal-year-end C corporations (returns due Sept. 15) can get extensions to April 15 until tax years beginning after 2025; after 2025, June 30 fiscal-year-end C corporations will have an Oct. 15 due date and can get extensions until April 15.
May 15 (Extensions Until Nov. 15)Form 990, Return of Organization Exempt From Income Tax (series).
July 31 (Extensions Until Oct. 15)