Last reviewed: 25 September 2026. For years, GSTR-3B was an editable summary — whatever ITC your books supported, you typed in. That era is ending. Outward liability has been locked to GSTR-1/1A from the July 2025 period, and GSTN's phased plan targeted the July 2026 tax period for hard-locking auto-populated B2B ITC in Table 4A of GSTR-3B to GSTR-2B. The July and August 2026 returns have now been filed. We have not been able to confirm a dated GSTN advisory that fixes the go-live of the Table 4A lock, so check what the GSTR-3B screen allows for your own period. The practical direction is not in doubt: GSTR-2B is no longer a passive statement but the output of your actions on the Invoice Management System (IMS), and your monthly ITC is decided invoice-by-invoice, before the 14th.
The three IMS actions and what they do
| Action | Effect on GSTR-2B | Use when |
|---|---|---|
| Accept | Flows into 2B as available ITC | Invoice matches your purchase record; goods/services received |
| Reject | Kept out of 2B; supplier is flagged | Not your invoice, duplicate, wrong GSTIN/value — supplier must fix via GSTR-1A |
| Pending | Excluded now; carried to a later period | Goods in transit, quality dispute, invoice received but not booked |
| No action | Deemed accepted — enters 2B | Default; safe only if you reconcile anyway |
Since October 2025, credit notes and specified amendments cannot sit pending beyond one tax period, and accepting a credit note requires you to declare the corresponding ITC reversal (full / partial / none if never claimed). GSTN also released an Excel-based offline IMS tool (April 2026) for bulk actions — useful once volumes cross a few hundred documents.
What hard-locking changes in practice
- Excess claims stop at the portal. Where claimed ITC exceeded 2B, DRC-01C notices used to follow the return. With locking, the mismatch is blocked at source.
- Timing gaps need Pending, not memory. Goods in transit on the 14th? Keep the invoice pending; take it next month. Accepting now and claiming later invites 2B-vs-3B confusion.
- Supplier discipline becomes your cash flow. A supplier who misses the 11th pushes your credit a month out. Vendor onboarding should now check filing frequency and track record — the same theme as our 7 checks before claiming ITC.
- Reversals remain your job. Blocked credits (Section 17(5)), Rules 42/43 apportionment and RCM self-invoicing stay manual. Locking removes typing errors, not judgment.
- Table 4B: ITC reversals, including Rules 42/43 apportionment and Section 17(5) blocked credit.
- Table 4D: ineligible ITC and credit you are restricting for other reasons.
- Table 3.1(d): reverse-charge liability on inward supplies, such as import of services and specified unregistered purchases.
These figures come from your own working, so the lock makes their accuracy more important, not less.
A separate change from the same round of portal changes: sections 37(5), 39(11), 44(2) and 52(15) of the CGST Act bar filing GSTR-1, GSTR-3B, the annual return and TCS returns after three years from their due date, and the portal has enforced this from the July 2025 tax period. A GSTIN with old unfiled returns should clear them before each three-year window closes, because after that the return cannot be filed at all.
Monthly IMS SOP for an accounts team
- By the 12th: export the IMS inward register; run a three-way match against the purchase register and GRNs.
- By the 13th: Accept matched documents; Reject wrong-party/duplicate ones with a note to the supplier; mark genuine timing gaps Pending. Action every credit note — remember the one-period limit.
- On the 14th: generate/verify GSTR-2B; recompute if late actions were taken; tie 2B to the ITC control account.
- Before the 20th: file GSTR-3B with reversals computed; log rejected invoices for supplier follow-up; escalate suppliers with two consecutive misses.
- Quarterly: reconcile cumulative 2B vs books vs 3B — the same working that feeds GSTR-9/9C at year-end.
Who feels this most
| Business | Pressure point |
|---|---|
| Traders with high invoice volumes | Bulk IMS actions each cycle — use the Excel offline tool with maker-checker |
| Manufacturers with goods-in-transit | Pending discipline at month-end cut-offs |
| Exporters and SEZ suppliers | ITC accumulation and refund workings must mirror IMS-driven 2B; an RFD-01 claim for accumulated ITC is checked against 2B, so IMS actions and the refund statement must agree |
| Businesses on QRMP suppliers | Credit lands quarterly unless suppliers use IFF — renegotiate terms |
| Foreign-owned subsidiaries | Shared-service and small local vendors often file quarterly, so credit arrives late and month-end ITC in the group reporting pack does not match 2B |
Indian subsidiaries of foreign groups usually report monthly to a parent that expects ITC to follow the books. Our foreign subsidiary accounting, CFO and FEMA team runs the IMS cycle and explains the 2B timing differences in the group pack.
Frequently asked questions
What exactly changes in GSTR-3B from the July 2026 tax period?
GSTN's phased plan targeted the July 2026 tax period for making auto-populated B2B input tax credit in Table 4A non-editable, so that it flows only from your GSTR-2B, which itself is built from your IMS actions. Phase 1 (from the July 2025 period) already locked auto-populated outward liability from GSTR-1/GSTR-1A. As of 25 September 2026 we have not been able to confirm a dated GSTN advisory that fixes the go-live of the Table 4A lock, so check the GSTR-3B screen and the latest portal advisory for your period. Either way, corrections belong in IMS and in supplier amendments via GSTR-1A, not in overtyping figures in 3B.
What is the Invoice Management System (IMS)?
A dashboard on the GST portal, live since 14 October 2024, where every invoice your suppliers report in GSTR-1/IFF appears for you to Accept, Reject or keep Pending. Accepted (and untouched, i.e., deemed-accepted) documents flow into GSTR-2B on the 14th; rejected ones stay out; pending ones carry forward.
If we take no action in IMS, do we lose ITC?
No — inaction means deemed acceptance and the invoice enters GSTR-2B. The risk runs the other way: ineligible or disputed invoices get deemed-accepted and inflate your 2B, and once 3B is locked to 2B you must reverse ineligible credit consciously. Deemed acceptance is not a substitute for purchase-register reconciliation.
How long can we keep an invoice pending?
Regular invoices can be kept pending for verification and taken in a later period within the Section 16(4) time limit. Credit notes and specified amendments, however, can remain pending for only one tax period (rule effective October 2025), and on accepting a credit note you must declare the ITC reversal — full, partial or none if credit was never claimed.
Does IMS change anything for suppliers?
Yes. A buyer’s rejection surfaces to the supplier, who can correct the document through GSTR-1A in the same cycle or a subsequent GSTR-1. Watching rejections has become part of monthly hygiene — unresolved ones create liability mismatches on the supplier side too.
Is manual ITC entry gone completely?
No. Reverse-charge ITC (self-invoices), ITC reversals under Rules 42/43 and ineligible-credit disclosures still involve your own computation and entry. What goes away is free-hand editing of the B2B ITC that auto-populates from GSTR-2B.
Can we still file an old GSTR-3B that we missed?
Only within three years of its due date. Sections 37(5), 39(11), 44(2) and 52(15) of the CGST Act bar filing GSTR-1, GSTR-3B, the annual return and TCS returns after three years from the due date, and the portal has enforced this from the July 2025 tax period. A return older than that can no longer be filed, so any pending return should be filed before its three-year window closes.
We build the monthly reconciliation workpapers, IMS action SOP and vendor-compliance tracker — and handle your filings.
GST Compliance ServicesGST Notice HandlingTalk to usThis article reflects the GST law and the GST portal position as we could confirm them on 25 September 2026; phased rollouts can shift, so check the latest portal advisories before relying on a date. It is general information, not professional advice — consult a Chartered Accountant for your specific situation.