GSTR-3B: due dates and the July 2025 hard-lock on auto-populated liability

GSTR-3B is the summary return for paying tax. From the July 2025 period, liability auto-populated from GSTR-1/1A/IFF cannot be edited in 3B, so corrections go through GSTR-1A.

Due dates

• Monthly filers: 20th of the following month.
• QRMP filers: quarterly GSTR-3B by the 22nd or 24th of the month after the quarter, depending on the State group. For the first two months of a quarter, tax is paid through PMT-06 by the 25th (fixed-sum or self-assessment method).

Hard-lock from the July 2025 tax period

• GSTN Advisory No. 606 (7 June 2025): from the July 2025 period (filed in August 2025), liability auto-populated in GSTR-3B from GSTR-1, IFF and GSTR-1A is non-editable.
• To change it, amend outward supplies through GSTR-1A for the same period before filing GSTR-3B.
• Implication for firms: finalise sales data and review GSTR-1 carefully. Month-end "adjust in 3B" is no longer possible.

Interest and late fee

Interest at 18% p.a. applies on tax paid late (Section 50(1)), on the portion paid in cash. Late fees are charged per day of delay, with lower amounts for nil returns and turnover-based caps notified by CBIC.