The Deadline to file corporate tax returns (forms 1120, 1120A, and 1120S) is Monday March 16th, 2015. Most corporate returns are required to be filed electronically therefore they must be sent to the IRS before midnight on the 16th. If for some reason you are filing a paper corporate tax return, the post mark on the envelope must show 11:59pm or earlier in order to avoid late filing penalties.
If you require more time to file your corporate return, you can request a 6-month extension by filing federal Form 7004 and any corresponding state(s) extensions, however these too must be electronically filed or mailed before the March 16th Deadline.
If you require immediate assistance regarding filing your corporate return(s), contact an R&G Brenner professional before the deadline.