GSTR1 and GSTR3B, monthly or quarterly depending on your scheme and turnover.
A minimum number per year, spaced according to the Companies Act, with proper notice and recorded minutes.
These are the ones that get missed, because they are not on a calendar.
Keep a single calendar with reminders 15 days early.
It is recoverable and it gets more expensive every day.
Every recurring filing a small Indian private limited company owes, roughly when it falls due, and which ones carry penalties that grow every day you are late.