Compliance calendarHard deadline
Statutory deadline
GSTR-1 due date
GSTR-1 is what your buyers' input tax credit is built from, so a late one is their problem as well as yours.
GSTR-1
Outward supplies for last month
Falls due
11th of every month
Applies if
you file GST monthly
Extensions happen. These are the statutory dates. The CBIC and CBDT extend them often enough that you should confirm against the official portal before relying on one — particularly in the first year of a change. Cortex warns you ahead of the statutory date, which is the one you can plan around.
Stop tracking this by hand.
Cortex watches every statutory date that applies to you alongside your receivables, your payables and the MSME 45-day clock — and emails you before one costs you money, rather than after. Upload a Tally, Vyapar or Busy export and it reads your numbers as they come.
General information, not tax advice. Your own dates depend on your registration, turnover and constitution — check with your CA.