Your annual corporate income tax returns are due on March 15th for calendar year filers. Otherwise you will need to file your tax return by the 15th day of the second month after the close of your fiscal year (year ending on a date other than December 31st).

Please note: You may request a six month extension to file your income tax returns but the extension must be postmarked by the above referenced dates.
Other important dates to keep in mind:
To Be Filed Due Dates
Partnership Tax Returns April 15th
Sole-Proprietors April 15th
IRS Employer Payroll Returns January 31st, April 30th, July 31st, October 31st
NYS Employer Payroll Returns January 31st, April 30th, July 31st, October 31st
NYS Sales Tax Returns March 20th, June 20th, September 20th, December 20th
NJ Sales Tax Returns January 20th, April 20th, July 20th, October 20th