Business Tax Extension Deadline 2024 S Corporation. S corps and partnerships can still get an extension on march 15, and the last day for c corps to file for an extension is april 15. If an s corporation has successfully filed for an extension, the new due date would be the 15th day of the ninth month following the end of the corporation’s tax year.

S corporation tax return/ extension deadlines. This is the cutoff for electing to be taxed as an s corp for the current year.