GST Return Filing Guide: GSTR-1, GSTR-3B, and Due Dates Explained

Most regular GST-registered businesses deal with two returns every filing cycle: GSTR-1, which reports your outward supplies (sales), and GSTR-3B, the summary return where you declare tax liability and pay it. They serve different purposes and missing either one has separate consequences.

GSTR-1 — outward supplies

GSTR-1 is due on the 11th of the following month for monthly filers, or the 13th of the month after the quarter for businesses on the QRMP (Quarterly Return, Monthly Payment) scheme. This return is what populates your buyers’ GSTR-2B, so a late or incorrect GSTR-1 directly delays their input tax credit — not just yours.

GSTR-3B — summary return and tax payment

GSTR-3B is due on the 20th of the following month for monthly filers. QRMP taxpayers file quarterly, with due dates staggered at the 22nd or 24th depending on which state or union territory the principal place of business is registered in. This is the return that actually settles your tax liability, so even if GSTR-1 is filed on time, unpaid tax on GSTR-3B still accrues interest at 18% per annum.

Who qualifies for QRMP

Businesses with aggregate turnover up to ₹5 crore in the preceding financial year can opt into QRMP, filing GSTR-1 and GSTR-3B quarterly while still paying tax monthly through a simple challan (PMT-06). It reduces the filing burden without deferring tax payment.

Beyond the monthly cycle

• GSTR-9 — annual return, due 31 December following the financial year, mandatory above a turnover threshold
• Late fee on GSTR-3B — accrues per day of delay, subject to a cap that varies by turnover slab
• Reconcile GSTR-2B against your purchase register every month — mismatched ITC is one of the most common notice triggers

The biggest source of GST notices we see isn’t late filing — it’s ITC claimed on GSTR-3B that doesn’t match what shows up in GSTR-2B. Reconciling both every month before you file is the single highest-leverage habit for staying out of trouble.