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Since October 2024, GSTR-2B contents are determined by the recipient's Accept, Reject, or Pending actions in the Invoice Management System — making the old two-way purchase register vs GSTR-2B reconciliation structurally incomplete. The 14th-to-20th six-day IMS window forces bulk invoice review before GSTR-3B filing.
Three-way matching compares purchase register against IMS pending queue against the resulting GSTR-2B on invoice number plus supplier GSTIN plus tax period. Auto-recommended IMS actions (Accept, Reject, Pending) are generated from the purchase-register match so the finance team only reviews exceptions. Once IMS actions are posted, the reconciliation re-runs against the updated GSTR-2B.
Purchase-register-to-IMS mapping rules, auto-action recommendations per match type (exact, partial, orphan), six-day window scheduler aligned to the 14th-20th cycle, and amendment tracker for mid-period IMS changes.
IMS action recommendation list ready for one-click submission, post-action GSTR-2B aligned with the purchase register, Pending queue for roll-forward, and audit trail linking every GSTR-3B ITC claim to the IMS decision that produced it.
Reconciling GSTR-2B against a purchase register was the complete ITC workflow before October 2024. That two-source comparison still works — but it now produces incorrect results because GSTR-2B values are no longer static. Since the Invoice Management System went live, GSTR-2B reflects the recipient’s own Accept and Reject decisions. A finance team that skips IMS is effectively letting the portal make those decisions by default, inheriting whatever the system assigns rather than confirming what their purchase records show.
What Changed After IMS Went Live in October 2024
Before IMS, the GSTR-2B was auto-populated directly from suppliers’ GSTR-1 filings. The recipient had no input into what appeared in GSTR-2B — you reconciled your purchase register against whatever the portal generated.
After IMS (October 14, 2024 onwards), GSTR-2B is still generated on the 14th of each month, but its contents reflect IMS actions taken by the recipient. A supplier’s invoice now lands in IMS first. The recipient’s Accept, Reject, or Pending decision determines whether that invoice appears in GSTR-2B for the current month.
The GST portal at www.gst.gov.in made IMS accessible through the GSTR-2B dashboard with a separate tab for actionable review. For October 2024 onwards, all inward supplies from GSTR-1 filers are visible in IMS before GSTR-2B is finalised.
This structural change means the input to your ITC reconciliation is no longer just GSTR-2B. It is the IMS-reviewed-and-confirmed subset of what suppliers have filed.
The Difference Between IMS, GSTR-2A, and GSTR-2B
| Statement | Type | Updated | Recipient Action | Use in Reconciliation |
|---|---|---|---|---|
| GSTR-2A | Dynamic | Real-time as suppliers file | None (read-only) | Monitor supplier filing compliance |
| IMS | Actionable | Updated after each GSTR-1 filing | Accept / Reject / Pending | Confirm or dispute inward invoices before GSTR-2B |
| GSTR-2B | Static | Generated 14th of each month | None (reflects IMS decisions) | Basis for ITC claim in GSTR-3B |
The three statements are sequential, not interchangeable. GSTR-2A is the early-warning view. IMS is the decision layer. GSTR-2B is the ITC-eligible output.
A finance team that reconciles only GSTR-2B to their purchase register is working at the output stage without managing the IMS decision stage that determines what the output contains.
The New Three-Way Reconciliation: Purchase Register vs IMS vs GSTR-2B
The complete ITC reconciliation process for FY 2025-26 and beyond has three data sources:
Source 1 — Purchase Register (ERP): Your internal record of all inward purchases, invoices received, GSTIN of suppliers, amounts, and tax breakdowns. This is your ground truth.
Source 2 — IMS Dashboard (GST Portal): The list of invoices your suppliers have declared in GSTR-1 and uploaded to IMS. This is the supplier’s declared position.
Source 3 — GSTR-2B (GST Portal): The ITC statement generated after IMS decisions are made. This is the ITC-eligible amount the system will allow you to claim.
The reconciliation runs in two stages: first, compare Purchase Register against IMS to identify discrepancies and make Accept/Reject/Pending decisions. Second, compare the resulting GSTR-2B against the Purchase Register to confirm that accepted invoices have correctly appeared and that ITC claimed in GSTR-3B does not exceed GSTR-2B.
Step-by-Step Reconciliation Process with IMS
Step 1 — Export purchase register for the month. Extract all inward invoices from your ERP for the reconciliation period. Key fields: supplier GSTIN, invoice number, invoice date, taxable amount, CGST, SGST, IGST.
Step 2 — Export IMS data from the GST portal. Log into GST portal, navigate to Services → Returns → IMS. Download the list of invoices in IMS for the current month.
Step 3 — Run the purchase register vs IMS comparison. For each invoice in IMS: does it match a record in the purchase register by GSTIN + invoice number + amount? Flag exceptions: invoices in IMS but not in purchase register (supplier uploaded invoice you haven’t received), or amounts that differ between the two sources.
Step 4 — Complete IMS actions. Based on the comparison: Accept all matched invoices, Reject invoices not in purchase register or with incorrect amounts, mark disputed or unverified invoices as Pending. Actions must be completed before the GSTR-3B filing deadline.
Step 5 — Download the final GSTR-2B. After IMS actions are complete (or as late as possible before the filing deadline), download the updated GSTR-2B. This now reflects your decisions.
Step 6 — Reconcile GSTR-2B to purchase register. Confirm that all Accepted invoices appear in GSTR-2B with correct amounts. The ITC claimed in GSTR-3B Table 4 should equal the ITC in GSTR-2B, adjusted for any Section 17(5) blocked credits that are Accepted in IMS but reversed in the return.
How IMS Decisions Affect GSTR-2B Values
The relationship between IMS and GSTR-2B is deterministic:
| IMS Action | Effect on GSTR-2B | ITC Available in GSTR-3B |
|---|---|---|
| Accept | Invoice included in GSTR-2B | Yes, for current month |
| Reject | Invoice excluded from GSTR-2B | No |
| Pending (no action) | Invoice excluded from current month’s GSTR-2B | Deferred to next month |
| Pending (explicit) | Same as no action — deferred | Deferred to next month |
A common misunderstanding: “Pending” does not mean the invoice disappears. It means the invoice defers to the next GSTR-2B cycle. Finance teams that use Pending as a holding pattern must track the deferred inventory and resolve it in the following month’s IMS review.
Reconciliation Errors That IMS Creates If Not Managed Properly
Error 1 — ITC claimed on Pending invoices: A team claims ITC from the purchase register without checking IMS status. The invoice is Pending in IMS and therefore absent from GSTR-2B. GSTR-3B ITC exceeds GSTR-2B ITC. DRC-01C notice issued for the difference if it exceeds ₹1 lakh or 20% of GSTR-2B ITC.
Error 2 — Rejected invoices that should have been accepted: The team rejects an invoice due to a minor narration difference, not realising it matches a purchase register entry. The ITC is lost for the month. Recovering it requires the supplier to file a GSTR-1 amendment, which reintroduces the invoice into next month’s IMS.
Error 3 — Pending invoice accumulation: Invoices marked Pending in successive months without resolution create a growing backlog. By the time they appear in GSTR-2B (when eventually Accepted), the ITC claim may fall outside the eligible claim window under the time limits specified in Section 16(4) of the CGST Act.
Error 4 — Multi-GSTIN reconciliation gaps: Businesses with multiple GSTINs must manage separate IMS dashboards for each registration. A Pending invoice on one GSTIN does not affect another. Teams using spreadsheet-based reconciliation typically discover multi-GSTIN IMS gaps at quarter-end rather than monthly.
Automation and IMS: What Your Reconciliation System Needs to Handle
The six-day window between GSTR-2B generation (14th) and GSTR-3B filing (20th) defines the operational constraint. For an organisation with 200 inward invoices per month, manual IMS review is feasible. For 2,000 invoices or multiple GSTINs, it requires an automated comparison.
A purpose-built GST reconciliation software needs to handle the following for IMS-era reconciliation: import purchase register data, pull IMS dashboard data via portal, execute the three-way match, flag exception categories (not in IMS, not in purchase register, amount mismatch, Section 17(5) overlap), and present the exception set for human decision before the filing deadline.
The output of this exception workflow feeds directly into GSTR-3B Table 4 ITC values and into the IMS action queue on the portal. Teams running this on spreadsheets are performing the same logic manually at a pace that does not fit the six-day window.
For organisations managing this across multiple entity types or reconciliation scenarios, reconciliation software built for India that handles GST alongside TDS and bank reconciliation in one workflow reduces the coordination overhead between different compliance processes that share the same underlying transaction data.