Certain tax return and extension due dates will change for taxable years ending on or after December 31, 2016, based on provisions included in the Surface Transportation and Veterans Health Care Choice Improvement Act of 2015 that was signed into law on July 31st, 2015. The changes represent years of lobbying by The American Institute of CPAs to have a more logical flow of tax return due dates, especially to have pass-through entity returns and the resulting Form K-1s due before individual and corporate tax returns affected by the information.
New Due Dates
The main change is that partnership tax returns are due a month earlier (two and half months after year end) on March 15th. C Corporations are now due three and half months after year end (see chart below for nuances related to ‘6/30’ C Corporation fiscal year-ends).

The table below highlights the new and existing original and extension due dates by form type.

ReturnCurrent Due DatesNew Due DatesNotes
Individual, Form 1040April 15th

Extendable to October 15th

April 15th

Extendable to October 15th

No changes
Partnership, Form 1065April 15th

Extendable to September 15th

March 15th

Extendable to September 15th

Fiscal year partnerships will have a due date the 15th day of the 3rd month after year-end with a six-month extension
S Corporation, Form 1120SMarch 15th

Extendable to September 15th

March 15th

Extendable to September 15th

No changes for S Corporation entities
C Corporation with a 12/31 Year-End, Form 1120March 15th

Extendable to September 15th

April 15th through 2025

Extendable to September 15th

2026 and thereafter: extendable to October 15th

The extension due date for calendar year-end C Corporations will remain the same through 2025 and then change by a month in 2026
C Corporation with a 6/30 Year-End, Form 1120September 15th

Extendable to March 15th

Pre-2026: September 15th

Post-2026: October 15th

C Corporations with 6/30 year-ends will not have their original due date change until 2026
C Corporation with all other Year-Ends, Form 112015th day of 3rd month after year-end

Extendable to the 15th day of 9th month after year-end

15th day of 4th month after year-end

Extendable to the 15th day of 10th month after year-end

For C Corporations with year-ends other than 12/31 or 6/30
Trusts & Estates, Form 1041April 15thApril 15thTrust and estate returns will have a 5 1/2 month extension
Exempt Organizations, Form 990May 15th

Extendable to August 15th

Second extension to November 15th

May 15th

Extendable to November 15th

Instead of two three-month extensions, Exempt Organizations will have one six-month extension