Exception:

However, a corporation with a fiscal tax year ending June 30 must file by the 15th day of the 3rd month after the end of its tax year. A corporation with a short tax year ending anytime in June will be treated as if the short year ended on June 30, and must file by the 15th day of the 3rd month after the end of its tax year. See Exhibit 3.14.2-24, Form 1120 (MFT 02) Family Estimated Tax Installment Payment, Return, and Extension Due Dates (EXCLUDES 1120-C, 1120-F D3 not checked, 1120-POL, and 1120-S), for more information.

For tax periods beginning prior to 2016 the Form 1120 return due date is the 15th day of the 3rd month after the end of the tax period. Example: A tax period ending December 31, 2015 is due March 15, 2016.

Tax entities not in existence the entire year may file a short period return. Requirements for filing the return and figuring the tax are generally the same as if the return was for a full tax year that ended on the last day of the short tax year.

Watch for any reprocessable returns.