Corporations and S Corporations
Form 1120 and Form 1120S (or Form 7004). These forms are due on the 15th day of the 3rd month after the end of the corporation's tax year. S corporations must provide each shareholder with a copy of Schedule K-1 (Form 1120S) or a substitute Schedule K-1.
Estimated tax payments. Payments are due on the 15th day of the 4th, 6th, 9th, and 12th months of the corporation's tax year.
Form 2553. This form is used to choose S corporation treatment. It is due no more than two months and 15 days after the beginning of the tax year the election is to take effect or at any time during the preceding tax year.
For more information refer to TaxAct.com