March 15th is the deadline to file calendar year corporate tax returns (Forms 1120 and 1120S). Because that fell on a Saturday, Monday, March 17th is the deadline. If you’re not ready to file, file an extension. Download Form 7004 and mail it certified mail, return receipt requested. If you’re a C-Corporation and believe you owe tax, pay the amount you think you will owe.
Extensions can also be electronically filed.
Finally, don’t forget your state corporate returns (though not all states have the same deadline). Some states’ extensions are automatic while others are not.
