One key difference between a single member LLC and an S corporation is that S corporations require a separate business tax return (whereas single member LLC profits are reported on Schedule C of the owner’s tax return). This additional tax return is the Form 1120-S, U.S. Income Tax Return for an S Corporation. Most people know that the individual Form 1040 tax return is due April 15th, but when are S corp taxes due? For most businesses, the S corporation tax return is due March 15th following the end of the calendar year. The business can also file Form 7004, Application for Automatic Extension of Time to File Certain Business Income Tax, Information, and Other Returns, by March 15th, and receive an additional 6 months to file. This makes the extended deadline, September 15th. 

While a little more rare, S corporations can change their fiscal year end to a date that doesn’t follow the calendar year (December 31st). In this case, the S corporation tax return would be due by the 15th day of the third month following the end of the tax year. For example, if an S corporation had a fiscal year end of May 31st, the tax return would be due August 15th.

Regarding S corp tax payments, S corporations are pass-thru entities. This means the profit and loss from the S corporation “passes through” to the shareholder. S corps, themselves, don’t pay tax on the federal level. With that being said, certain states do assess a tax on S corp profits. For most states, payment is due by the same day as the tax return (March 15th).