a corporate return is due the 15th day of the third month following the end of its tax year. an extension gives it six more months to file. so a calender year 2021 return was due 9/15/2022. any taxes owed were due by the unextended due date. you need the Turbotax business version to do a corporate return which can only be done on a Windows PC. there is no online version.
https://turbotax.intuit.com/small-business-taxes/
