Calendar-Year Corporate returns and Partnership returns (Federal Forms 1120, 1120S, and 1065) are due September 15^th! This deadline is the absolute and final deadline to file returns for both corporations and partnerships, as no additional extensions are available. Late returns will be subject to the following penalties:

C-Corp (Form 1120) - Minimum penalty for late filing if a return is more than 60 days late is lesser of $135 or 100% of the amount of tax required to be show on the return.  If tax is due, the late filing penalty assessed is 5% of the unpaid balance per month or part of a month with a maximum of 25% plus interest.  However, the above penalties will not be imposed if the corporation can show the failure was due to reasonable cause and not willful neglect.

S-Corp (Form 1120S) - The penalty for failure to file a return is $195 per month per shareholder up to 12 months and is assessed against the corporation.  In addition, if tax is due, a late filing penalty may be imposed similar to the C-Corp, 5% of tax owner per month up to 25%, as well as the minimum penalty of the lesser of $135 or amount of unpaid tax if the return is more than 60 days late.  As with C-Corps, the penalties for failure to file an 1120S will not be imposed if reasonable cause is established.

Partnership (Form 1065) -  The penalty for failure to file is $195 per month per partner up to 12 months and is assessed against the partnership.  The penalty will be abated if the partnership can show reasonable cause, but please note it is much more difficult for a partnership to qualify for the reasonable cause exception.