- Active IMS validation: Taxpayers must review inward invoices and credit notes on the Invoice Management System (IMS) to accept, reject, or keep pending records.
- GSTR-2B recomputation: Whenever actions are taken on IMS after the 14th, taxpayers must trigger "Compute GSTR-2B" so that only validated ITC flows into GSTR-3B.
- Credit note linkage (Section 34): Rejecting a supplier’s credit note on IMS blocks the supplier’s tax reduction; accepting it requires corresponding ITC reversal by the recipient.
- Mandatory sequencing (Section 39(1)): GSTR-3B cannot be filed until GSTR-2B has been generated/recomputed for the tax period.
The monthly GST return filing process requires far closer coordination between purchase teams, accounts payable, and tax filers than in earlier years. With the rollout of the Invoice Management System (IMS) and the implementation of the amended Sections 34 and 39(1) from 1 October 2025, passive reliance on auto-populated GSTR-2B numbers is no longer sufficient.
1. End of Passive ITC Auto-Population
Previously, Input Tax Credit (ITC) figures were passively auto-populated from GSTR-2B into Table 4 of GSTR-3B on the 14th of each month. Under the current workflow, taxpayers must actively curate and validate inward supplies against their purchase register—ensuring that ineligible credits under Section 17(5), goods in transit where delivery has not yet been received under Section 16(2), and disputed bills are either kept pending or rejected before GSTR-3B is filed.
2. Invoice Management System (IMS) & GSTR-2B Regeneration
Every B2B invoice, debit note, or credit note saved or filed by your suppliers in GSTR-1 / IFF appears in real time on your IMS dashboard. Between the 14th and the 20th of the month, your finance team must follow a strict four-step sequence:
- Log in to the IMS Dashboard on the GST portal and reconcile inward records with your purchase register.
- Take action on each record: Mark valid received supplies as Accept (or leave as default deemed-accepted), mark erroneous bills as Reject, or mark goods-in-transit / under-verification invoices as Pending (to be claimed in a subsequent month).
- Click "Compute GSTR-2B": Any action taken on IMS after the draft GSTR-2B is generated on the 14th requires you to regenerate/recompute GSTR-2B on the portal.
- Proceed to GSTR-3B: Only after the updated GSTR-2B is generated will the revised ITC figures populate into GSTR-3B for filing.
3. Credit Note Taxability & IMS Actioning (Section 34)
Inward credit notes issued by suppliers cannot be kept "Pending" on IMS—they must either be accepted or rejected. If a recipient accepts a credit note, their eligible ITC in GSTR-2B/3B is reduced accordingly. If the recipient rejects it because the commercial return or discount was not agreed upon, the supplier’s output tax liability is increased by that amount.
4. No GSTR-3B Without Validated GSTR-2B
In line with Section 39(1) and GSTN portal validation rules, GSTR-3B filing is blocked if there are uncomputed IMS actions or if GSTR-2B has not been generated for the period. Leaving invoice reconciliation until the afternoon of the 20th risks missing the statutory filing deadline.
5. Recommended Monthly Calendar for Businesses
- By the 10th of the month: Reconcile outward sales and file GSTR-1 ahead of the 11th deadline.
- 14th to 16th of the month: Download the initial GSTR-2B and IMS inward list, match against your Tally / Zoho purchase register, and identify missing bills or unagreed credit notes.
- By the 17th of the month: Complete all Accept / Reject / Pending actions on IMS and click "Compute GSTR-2B".
- By the 19th of the month: Verify cash/credit ledger balances, deposit net GST via Challan PMT-06, and file GSTR-3B.
Want us to handle your monthly IMS & GSTR-3B reconciliation?
We manage the entire monthly GST cycle—GSTR-1, IMS line-by-line matching, vendor follow-up lists, and on-time GSTR-3B filing.