The monthly cycle
A regular taxpayer files GSTR-1 with outward supply details by the 11th, and GSTR-3B with the summary and tax payment by the 20th. QRMP filers move to quarterly returns with monthly payment, on staggered dates by state group.
The cycle is unforgiving in one specific way: non-filing blocks the next period's GSTR-1 and your e-way bill generation, so one missed month quickly becomes an operational problem.
The part that costs real money
Late fees and interest are annoying but bounded. Lost input tax credit is not. Credit is available on the basis of GSTR-2B, which depends on your supplier filing correctly and on time.
Credit for a financial year must generally be claimed by 30 November of the following year or the date of filing the annual return, whichever is earlier. After that it is gone — which is why reconciliation is a monthly discipline, not an annual clean-up.
Annual filings
GSTR-9 is due by 31 December following the financial year, with GSTR-9C where turnover crosses the notified limit. Since January 2026 late fees on annual returns are levied automatically, so the date now has an immediate cost.
The annual return is where differences between your books and your returns get explained. Preparing it from ledgers rather than by copying the monthly returns is what makes that possible.
A practical rhythm
Reconcile purchases against GSTR-2B in the first week of the month, prepare GSTR-1 by the 8th, and leave the tax computation and GSTR-3B for the second week. That sequence means credit issues surface while the vendor can still fix them.
Our downloadable compliance calendar sets out the recurring dates in one page.
This is general information, not advice for your case.
Figures and dates apply to the financial year stated in the article and can change by notification. Bring your own position to a consultation and we will confirm what actually applies.