A S BANKA ADVISORS

A quiet but fundamental change has reshaped how GST returns work in India. Since the July 2025 tax period (returns filed from August 2025), the auto-populated outward tax liability in Form GSTR-3B is hard-locked. The figures flowing in from your GSTR-1, IFF and GSTR-1A can no longer be edited directly in GSTR-3B. Pair that with the Invoice Management System (IMS) now governing input tax credit, and the picture is clear: your GST liability and your credit are both decided upstream, not in the return where teams used to make last-minute adjustments. For founders and finance teams, the “fix it in 3B” era is over.

What “hard-locking” actually changed

GSTR-3B is the summary return through which tax is paid, filed under Section 39 of the CGST Act, 2017 read with Rule 61 of the CGST Rules, 2017. For years the portal auto-populated it from GSTR-1 but still allowed manual edits before filing. That editing window was the single largest source of GSTR-1 versus GSTR-3B mismatches, and was frequently used to adjust or suppress liability. Following GSTN Advisory No. 606 dated 7 June 2025, the auto-populated outward supply liability in Tables 3.1 and 3.2 became non-editable from the July 2025 tax period. In plain terms: whatever you declare in GSTR-1 is exactly what you pay in GSTR-3B.

How you correct an error now

Because GSTR-3B can no longer be edited, corrections have shifted entirely upstream, and timing now matters more than it ever did:

• Same period: Use GSTR-1A to fix a wrong value, a missed invoice or a wrong GSTIN for the current period, before you file GSTR-3B, so the corrected figure auto-populates into the locked return. GSTR-1A was introduced by Notification No. 12/2024-Central Tax dated 10 July 2024 and is available only once per period, up to the actual filing of that period’s GSTR-3B.
• Later discovery: If the period has closed, you amend in a subsequent GSTR-1. There is no longer any way to patch it inside GSTR-3B.
• One trap to note: a change to the recipient’s GSTIN cannot be amended through GSTR-1A. That correction has to wait for a future GSTR-1.

The practical consequence is simple but demanding: reconciliation has to happen before you file GSTR-3B, not as a year-end clean-up.

IMS now decides your input tax credit

If liability is locked from your outward returns, credit is increasingly governed by the Invoice Management System. On IMS you see every inward invoice and credit note uploaded by suppliers, and you take one of three actions on each. Accept lets the invoice flow into your GSTR-2B as eligible credit. Reject excludes it, for invoices that do not belong to you or are incorrect. Pending carries it forward to a later period and defers the credit. Because GSTR-2B is built from these actions, ITC has become an active monthly reconciliation task, not a passive auto-population. Ignore IMS and you either lose credit you were entitled to, or claim credit on invoices you never validated.

What is expected around July 2026

The liability side is already locked. The widely indicated next step is hard-locking the auto-populated input tax credit in Table 4 of GSTR-3B, so that ITC too must come strictly from GSTR-2B as shaped by IMS. Advisory commentary points to a target of around July 2026. Read this carefully: as of now this is an indicated timeline, not a notified date. A GSTN advisory fixing a firm go-live had not been issued at the time of writing. Treat July 2026 as the direction of travel, prepare your reconciliation accordingly, and confirm the actual date against the official GSTN advisory before you change filing practices.

What this means for your business

For finance teams, the answer is a monthly cadence: file an accurate GSTR-1, reconcile to your books, fix any error through GSTR-1A before GSTR-3B, and action every invoice in IMS. For founders and MSMEs, the real exposure is working capital. If a supplier has not uploaded an invoice, or you have not accepted it in IMS, that credit will not appear in GSTR-2B and you may end up paying more tax in cash. The lever you still control is accuracy at source: clean outward returns, disciplined IMS action, and suppliers chased before the credit slips. Build that habit now, well before any Table 4 lock arrives.

Download the full carousel PDF for a slide-by-slide summary you can share with your finance team.

Need help building a monthly GST reconciliation cadence that holds up under hard-locking? Talk to an expert: https://calendly.com/asbanka-info/30min