GST Return Due Dates for FY 2025-26: GSTR-1, 3B, 9 Calendar

GST compliance runs on three overlapping rhythms

GST compliance for FY 2025-26 runs on three overlapping cadences: monthly returns for regular taxpayers, quarterly returns for QRMP filers, and annual returns that reconcile the whole year. Managing all three across a mixed client base — some monthly, some quarterly, a few on composition — is where most GST practice tracking breaks down without a system that ties the due date to each client's specific filing category.

The master due-date table

Why the QRMP due date depends on your state

Taxpayers with turnover up to ₹5 crore can opt into the Quarterly Return Monthly Payment scheme, filing GSTR-1 and GSTR-3B quarterly while paying tax monthly via a simple challan. GSTR-3B's QRMP due date splits by state group: Group A (Maharashtra, Gujarat, Karnataka, Tamil Nadu, and most western and southern states) files by the 22nd, while Group B (Delhi, Uttar Pradesh, Rajasthan, and most northern and eastern states) files by the 24th. This split is the single most common source of due-date confusion for firms with clients registered across multiple states.

How GSTR-2B feeds into ITC claims

The nine-day gap between GSTR-1 (11th) and GSTR-3B (20th) for monthly filers exists so that a recipient's input tax credit auto-populates in their GSTR-2B before their own GSTR-3B is due. A late GSTR-1 doesn't just risk a late fee on that return — it delays every recipient's ITC claim, which is frequently the first thing a client's vendor calls about when a filing slips.

Worked example: a QRMP filer across the quarter

Maheshwari Textiles Pvt Ltd, registered in Rajasthan (a Group B state) with turnover of ₹3.2 crore, opts into QRMP. For Q2 FY 2025-26 (July–September 2025):

• GSTR-1 for the quarter is due 13 October 2025, regardless of state group.
• GSTR-3B for the quarter is due 24 October 2025, since Rajasthan falls in Group B.
• Monthly tax payments for July and August are still made via a simple challan (PMT-06) even though no return is filed those months — only September's payment is reconciled with the actual GSTR-3B filing.

A common error here is assuming the 22nd deadline (Group A) applies simply because it's the date most GST reference material lists first — Maheshwari Textiles' actual deadline is two days later, on the 24th.

Common mistakes in GST return filing

• Applying the wrong QRMP GSTR-3B due date by mixing up Group A and Group B state classifications.
• Skipping the optional Invoice Furnishing Facility (IFF) for QRMP filers, which can delay a B2B recipient's ITC claim until the full quarterly GSTR-1 is filed.
• Missing that two or more consecutive GSTR-3B defaults can block e-way bill generation for that GSTIN.
• Confusing GSTR-9 (annual return) with GSTR-9C (reconciliation statement) thresholds — the latter applies only above a higher turnover level.
• Leaving reconciliation between books and filed returns until year-end instead of catching mismatches monthly.

Turning the calendar into a workflow

The recurring nature of GST compliance — the same return, the same client, every month or quarter — is exactly the kind of work that shouldn't depend on someone remembering to create a task. A system that auto-generates GSTR-1 and GSTR-3B tasks for every client at the start of each cycle, assigned to the right team member with the correct due date already attached, removes this entire category of manual tracking. That's the core of what PracticeFlow's recurring task engine does for GST practitioners managing more than a handful of clients.