The return that must be filed is an 1120-S which if its using a FISCAL year that started in 9/19 and ends August 31, 2020 will be due 11/15/2020.
If you are going to choose a CALENDAR year then the first short year return is due 3/15/20 .. so please seek local professional assistance in either bookkeeping and/or tax prep to get educated ... the penalties for doing things incorrectly or late are severe.
https://www.aicpa.org/interestareas/tax/resources/compliance/downloadabledocuments/due-dates-summary...
