GST Due Dates in October 2026

Every GST deadline in October 2026

GSTR-1 (monthly filers) is due 11 October 2026 (For the September 2026 period). GSTR-3B (monthly filers) is due 20 October 2026 (For the September 2026 period). GSTR-1 (QRMP quarterly) is due 13 October 2026 (For the quarter just ended). GSTR-3B (QRMP quarterly) is due 22/24 October 2026 (22nd for Category X states, 24th for Category Y states). CMP-08 (composition) is due 18 October 2026 (For the quarter just ended).

This list covers the deadlines that fall due during October 2026 itself — for monthly filers, that means the previous month's GSTR-1 and GSTR-3B, since both returns are always due in the month after the period they cover. FY 2026-27 is the current financial year as of October 2026.

Get this personalised to your actual filing scheme

Not every deadline above applies to every business — which ones are relevant depends on filing scheme (regular, QRMP, or composition), turnover, and any additional GST registrations held. The full GST Due Date Calculator builds a personalised calendar from your specific profile, rather than the general list shown here.

Why the due month differs from the period covered

A recurring source of confusion is that a deadline falling in October 2026 almost always covers the PREVIOUS month or quarter's activity, not October itself — GSTR-1 and GSTR-3B due this month report on last month's supplies, and any quarterly filing due this month covers the quarter that just ended. Keeping this distinction clear matters most at financial-year boundaries, where a deadline can fall in one financial year while covering activity from the year before it.