It's not penalty. It's called "Late Fee" also you ll be pay the Late fee amount in "FEE" head at the time of creating Challan...
The October Month GSTR 3B return date 20th November. You can't filed the return on or before 20th November then the penalty calculatd from 21st November to 14th December. The no. of days are calculated 24 days...
You ll be pay CGST - 24 X 25 = 600 SGST - 24 X 25 = 600.....
CAclubindia
