global Tax Corporate Tax Deadline Fast Approaching March 10, 2014 The next major deadline coming up is for corporate tax returns on March 17th. Even if you are well prepared this year, sometimes it’s easy to overlook deadlines while dealing with day-to-day business. The next major deadline coming up is for corporate tax returns on March 17th. March 17, 2014The deadline for the 2013 calendar year corporate tax returns, which include Forms 1120 and 1120S, is March 17th. The original deadline for corporate returns is March 15th, but this falls on a Saturday, so this year the deadline is being pushed back to the next business day, Monday, March 17th. An Automatic Extension (Form 7004) can be filed, and is also due by March 17th. This gives businesses an additional six months to file the return; payment is still due on March 17th. We recommend that you submit payment when applying for the extension.