Rule 37A: reverse ITC if your supplier didn't file GSTR-3B (deadline 30 November)

Rule 37 punishes you for not paying your supplier; Rule 37A punishes you because your supplier didn't pay the government — and its deadline is a hard 30 November.

Since December 2022, the "supplier reported the invoice but never actually paid the tax" gap has its own rule. It bites in exactly one scenario, on exactly one calendar.

The trigger, precisely

1. Supplier reported your invoice in GSTR-1 → it reached your GSTR-2B → you claimed the ITC. ✔
2. But the supplier never filed GSTR-3B for that same period — the tax was reported, not paid.
3. If that 3B is still unfiled on 30 September of the following financial year, Rule 37A activates:
4. You must reverse that ITC in a GSTR-3B filed on or before 30 November.

Reverse by 30 November → no interest. Discover it later (or let an auditor discover it) → reversal plus 18% interest under Section 50.

A ₹ example

FY 2025-26: you claimed ₹36,000 ITC on invoices from Mehta Enterprises in January 2026. Mehta filed GSTR-1 (so your 2B looked fine) but never filed January's GSTR-3B — and still hasn't on 30 September 2026.

• In a GSTR-3B filed by 30 November 2026, you reverse ₹36,000. No interest.
• Mehta finally files and pays in March 2027 → you re-claim ₹36,000 in your next 3B.
• Had you not noticed until a 2028 audit: ₹36,000 + roughly two years of 18% interest ≈ ₹13,000 extra, plus the argument.

Why this rule exists

It closes the classic fake-ITC loop — firms that file GSTR-1 (creating credit for buyers) while skipping GSTR-3B (never paying). FY24-25's ₹1.01 lakh crore fake-ITC detection is the scale of that game. Rule 37A quietly moves the enforcement to you, the buyer, on a fixed calendar.

The defence: watch 3B, not just 2B

Your GSTR-2B only proves GSTR-1 was filed. The supplier habit that matters for Rule 37A is GSTR-3B filing, which is public per supplier — the "GSTR-1 filed, 3B missing" red flag in our return-status guide is precisely the Rule 37A early warning. Check top suppliers monthly (bulk checker), escalate the laggards while the amount is one month's, not a year's.

Calendar rule: every October, list suppliers with unfiled 3Bs for the previous FY; reverse in the October or November 3B — inside the interest-free window.

GST Sathe (Dukaan+ AI) tracks supplier 3B status against your claimed ITC year-round and flags Rule 37A exposure in October automatically — with the re-claim reminder when the supplier eventually pays. See pricing →

Sources

• Rule 37A, CGST Rules (Notification 26/2022-CT); Section 41(2), CGST Act
• GSTN advisory on Rule 37A ITC reversal communications; Section 50 (interest)