Last updated: 25 June 2026. For years, GSTR-3B was a form you could override. The portal auto-filled your numbers, but if they looked wrong, you typed over them and filed. That era is ending in stages. Since the July 2025 tax period, your outward liability has been hard-locked — non-editable, no override button. The next field in line is the one that matters most to your cash flow: input tax credit in Table 4. This guide explains what has already locked, what Table 4 hard-locking would mean, and the reconciliation habits that protect your credit before it does.
Applicability Note: This guide reflects GST provisions, GSTN advisories, and CBIC notifications applicable as of 25 June 2026. Outward-liability hard-locking is in force; ITC (Table 4) hard-locking is anticipated, not yet notified — no advisory or notification has fixed an effective date as of June 2026. Timelines and field-level behaviour may change. Always verify the current position on gst.gov.in or with a GST professional before acting on your returns.
What "Hard-Locking" Actually Means
Hard-locking is the portal making an auto-populated cell non-editable. The figure flows in from an upstream source, and you can no longer type over it. There is no "Proceed Anyway" prompt and no manual override — if the number is wrong, you fix it at the source, not in GSTR-3B.
The Government is rolling this out field by field, not all at once. It helps to think of it in two phases:
- Phase 1 — Outward liability (live since July 2025). Tables 3.1 and 3.2, auto-populated from your GSTR-1/IFF, are locked.
- Phase 2 — Input tax credit (expected, not yet notified). Table 4, auto-populated from your GSTR-2B, is the anticipated next step.
Phase 1 Is Already Here: Outward Liability Is Locked
From the July 2025 tax period — that is, the GSTR-3B most taxpayers filed in August 2025 — the auto-populated outward liability in Tables 3.1 and 3.2 became non-editable. This was announced in GSTN Advisory No. 606 dated 7 June 2025. The values come straight from your GSTR-1, IFF, or GSTR-1A, and the portal no longer lets you edit them inside GSTR-3B.
The practical consequence: if you spot a mistake in your outward figures, you cannot patch it in GSTR-3B. You correct it at the source by filing GSTR-1A for the same tax period before you file GSTR-3B. GSTR-1A is now the formal correction window for outward supplies. Miss it, and you carry the error into the locked return.
The shift in mindset: GSTR-3B used to be where you fixed things. Now it is where things are finalised. The fixing happens upstream — in GSTR-1/GSTR-1A for sales, and (as we'll see) in IMS for purchases.
Phase 2: What ITC Hard-Locking Would Change
Table 4 is where your input tax credit is claimed. Today it auto-populates from your GSTR-2B, but you can still edit it. The anticipated Phase 2 change is that the B2B ITC in Table 4A would be restricted to what auto-populates from GSTR-2B — you would no longer be able to claim more ITC in GSTR-3B than your GSTR-2B reflects.
Not every cell in Table 4 is expected to lock. The fields that involve genuine taxpayer computation are likely to stay editable, because the portal cannot calculate them for you:
| Table 4 field | What it captures | Likely status under Phase 2 |
|---|---|---|
| 4A(5) — All other ITC | B2B credit from suppliers, via GSTR-2B | Expected to be locked to GSTR-2B |
| 4A(2) — Import of services | IGST on imported services you self-assess | Likely remains editable |
| 4B — ITC reversal | Reversals under Rules 38, 42, 43, Section 17(5) | Likely remains editable |
| 4D — Reclaim / ineligible | Reclaimed credit and reporting-only fields | Likely remains editable |
Important: the field-level detail above reflects the direction signalled by GSTN and professional commentary — it is not a notified design. The one safe planning assumption is the headline: your claimable B2B ITC will be whatever your GSTR-2B says it is. So the real question becomes: who controls your GSTR-2B?
The Link Most People Miss: GSTR-2B Is Now Built in IMS
Here is why Phase 2 is not really a "GSTR-3B change" at all. Since 1 October 2025, your GSTR-2B is built from the records you accept in the Invoice Management System (IMS) — Section 38 of the CGST Act was substituted to this effect via Notification No. 16/2025-Central Tax dated 17 September 2025.
Follow the chain: IMS decides your GSTR-2B → and a hard-locked Table 4 would tie your ITC to that GSTR-2B. In other words, once Table 4 locks, the only way to control your input tax credit is to control your IMS dashboard. A wrong invoice you let auto-accept in IMS won't just inflate your GSTR-2B — it will be the only credit you're allowed to claim, with no chance to override it down in GSTR-3B.
For the mechanics of accepting and rejecting records, see our companion guide on how to use IMS before GSTR-2B locks.
One Thing That Does Not Change: Section 16(2)
Hard-locking controls what appears in your return. It does not certify that the credit is lawful. The conditions of Section 16(2) still apply independently: you must have received the goods or services, hold a valid tax invoice, and the supplier must have actually paid the tax to the government. A figure auto-populating into a locked Table 4 is not a guarantee you may keep it — if it fails Section 16, it must still be reversed, with interest at 18% per annum under Section 50. Locking narrows your input; it does not lower your standard of proof.
How to Prepare Now — Before Table 4 Locks
The taxpayers who will sail through Phase 2 are the ones who already treat GSTR-2B as final. Build these habits now:
- Review IMS every month, like a bank statement. Accept genuine purchases, reject anything that isn't yours, and never let records auto-accept by inaction. Your IMS discipline today is your ITC ceiling tomorrow.
- Reconcile GSTR-2B against your purchase register every period. Chase missing invoices with suppliers before the 14th, when the draft GSTR-2B generates. Credit a supplier hasn't reported won't be in your 2B — and under a locked Table 4, you can't add it manually.
- Use GSTR-1A for outward corrections. Since Table 3 is already locked, make it routine: spot an error in sales, fix it via GSTR-1A before filing GSTR-3B.
- Tighten supplier follow-up. Your credit now depends on your suppliers filing correctly and on time. Make timely, accurate GSTR-1 filing a condition in your vendor terms.
- Keep your Section 16 evidence in order. Goods-receipt notes, tax invoices, and proof of payment — so every auto-populated credit can survive scrutiny, not just appear in the return.
For the reconciliation method itself, see GSTR-2B Reconciliation Before GSTR-3B.
Key Takeaways
- Outward liability is already locked. Tables 3.1 and 3.2 are non-editable from the July 2025 tax period, per GSTN Advisory No. 606 dated 7 June 2025. Correct outward errors via GSTR-1A before filing GSTR-3B.
- ITC hard-locking (Table 4) is anticipated, not notified. The GSTN roadmap signals it around 2026, but as of June 2026 no advisory or notification has fixed an effective date. Plan for it; don't assume a confirmed date.
- Expect Table 4A B2B ITC to lock to GSTR-2B. Computation fields (4A(2) import of services, 4B reversals, 4D reclaims) are likely to stay editable.
- Control IMS to control ITC. GSTR-2B is built from your IMS actions; a locked Table 4 makes your IMS dashboard the gate your credit passes through.
- Section 16(2) still governs legality. Auto-population is not entitlement — receipt, valid invoice, and tax paid still apply, and wrongly availed ITC reverses with 18% interest under Section 50.
Frequently Asked Questions
Is GSTR-3B ITC (Table 4) hard-locked right now?
No. As of June 2026, only the outward liability in Tables 3.1 and 3.2 is hard-locked (from the July 2025 tax period). Table 4 still auto-populates from GSTR-2B but remains editable. ITC hard-locking is an anticipated next phase; no GSTN advisory or CBIC notification has fixed an effective date yet. Verify the current position on the GST portal before filing.
When will Table 4 ITC hard-locking start?
There is no officially notified date. GSTN's roadmap and professional commentary point to it arriving around 2026, but until an advisory or notification is published on gst.gov.in, no date is confirmed. Treat it as expected and prepare your reconciliation now, rather than waiting for a deadline.
If my ITC is wrong after Table 4 locks, how do I fix it?
The expected design ties Table 4A B2B credit to GSTR-2B, and GSTR-2B is built from your IMS actions. So you correct ITC upstream — by rejecting wrong records in IMS and reconciling before the draft GSTR-2B generates on the 14th — not by editing GSTR-3B. This mirrors how outward errors are already fixed through GSTR-1A rather than in the locked return.
How is this connected to the Invoice Management System (IMS)?
Directly. Since 1 October 2025, GSTR-2B is generated from the records you accept (or are deemed to accept) in IMS. Because a hard-locked Table 4 would tie your ITC to GSTR-2B, your monthly IMS review effectively sets your claimable credit. Reviewing IMS carefully every month is the single most important habit to prepare for Phase 2.
Does a locked, auto-populated ITC figure mean the credit is safe to claim?
No. Hard-locking controls what shows in the return, not whether the credit is lawful. Section 16(2) still applies independently — you need receipt of the goods/services, a valid tax invoice, and proof the supplier paid the tax. ITC that fails these tests must be reversed with 18% interest under Section 50, even if it auto-populated into a locked field.
Disclaimer: This article is for informational purposes only and does not constitute professional tax advice. GST rules are subject to frequent changes through notifications, circulars, and GSTN advisories, and the Table 4 hard-locking discussed here is anticipated rather than notified. Please consult a qualified tax professional or verify the current provisions on the official GST portal (gst.gov.in) before making any compliance decisions.
Want your IMS and GSTR-2B reconciled every month so your ITC is right before Table 4 ever locks? Our GST experts can manage it → gstconsultancy.com