File back owed small business 2019 Tax Return ($25k Rev) & 2020 Tax Return ($534k Rev) – P&L & BS Completed

I need to file back owed small business S-Corp 2019 Tax Return ($25k Rev) & 2020 Tax Return ($534k Rev). Both of the 2019 and 2020 P&L & BS have been completed already by my book keeper. The business is an S-Corp that was established in Delaware, but the primary business address is in Illinois.