Compliance details last reviewed on 4 October 2026. Tax rules change often. This is general information, not tax or legal advice, so confirm specifics with your chartered accountant.
Most credit problems do not start in the return. They start weeks earlier, when a supplier invoice sits unmatched and nobody owns the chase.
This guide is a practical monthly routine for GSTR-2B reconciliation: what GSTR-2B is, what the Invoice Management System (IMS) changed, a seven-step process, how to classify mismatches, who signs off, and the mistakes that cost credit. It builds on the reconciliation workflow in our overview of B2B accounting workflows.
What GSTR-2B is and when it is generated
GSTR-2B is a static statement of input tax credit (ITC) built from what your suppliers report in their returns. A draft is generated on the 14th of each month. It is the starting point for input tax credit reconciliation: you compare it with your own purchase register to see which credit you can claim in GSTR-3B.
Two properties shape the routine:
- It is sequential. Next month's GSTR-2B is generated only after the previous month's GSTR-3B is filed. Skipping a month's filing delays the next statement.
- QRMP recipients get a quarterly GSTR-2B, so their routine runs quarterly.
Under Section 16(2)(aa), credit is allowed only where the invoice details are communicated to you in GSTR-2B, and Section 16(4) sets a claim deadline of 30 November following the financial year end. Both are secondary-source readings, so confirm the current wording with your CA.
What IMS changes in the routine
The Invoice Management System went live on the GST portal on 1 October 2024, and taxpayers could act on received invoices from 14 October 2024. GSTR-2B now reflects decisions you make on each supplier record: accept, reject or keep pending. A record you leave alone is deemed accepted when GSTR-2B is generated.
- Timing. You can act in IMS until you file GSTR-3B, but actions taken after the 14th appear only when you recompute GSTR-2B. A reconciliation done on the 14th version, followed by IMS actions, is already stale.
- Pending is a holding state, not a decision. A pending record stays in IMS until you act on it or the Section 16(4) cut-off passes. It carries no credit in the meantime.
- Rejection reaches the supplier. If you reject certain original credit notes or amendments, the supplier's liability rises in their next GSTR-3B. Reject deliberately, not to clear a list.
- Some documents skip IMS. Reverse charge (RCM), ICEGATE and ISD documents flow straight into GSTR-2B, so they need their own check.
- Newer features. From October 2025, IMS has an Import of Goods (Bill of Entry) section, and credit notes can be kept pending for one tax period, with the ITC reversal adjustable on acceptance. A GSTN advisory of 8 October 2025 says IMS leaves the auto-population mechanism unchanged and that you can regenerate GSTR-2B before filing GSTR-3B.
The 7-step monthly routine
- Wait for the draft GSTR-2B and note the date. Record when you downloaded it; you will recompute it before filing.
- Lock the purchase register for the period. Make sure every supplier bill for the month is booked, with supplier GSTIN, invoice number, date, taxable value and tax amounts. Late-booked bills are the commonest reason a "missing" invoice is actually in your inbox.
- Match invoice by invoice. Compare GSTR-2B against the purchase register, supplier by supplier. Start with exact matches on GSTIN, invoice number and date, then match the remainder on tolerance rules your team has agreed.
- Classify every unmatched line. Give each one a single cause from the table below. An unexplained variance is not a finished line.
- Act in IMS. Accept what matches. Keep disputed or unclear records pending while you chase. Reject only records that are wrong and will not be corrected, such as an invoice not meant for you.
- Recompute GSTR-2B. Regenerate it so your IMS actions are reflected, then re-run the match. This is the step teams skip.
- Sign off, then file GSTR-3B. A named reviewer approves the variance report. Only then is GSTR-3B filed on the recomputed figures.
How to classify mismatches
Five causes explain most differences between GSTR-2B and your register. Sorting them before acting stops a clerical error from becoming a rejection.
| Mismatch type | Likely cause | First fix |
|---|---|---|
| In register, not in GSTR-2B | Supplier has not reported it yet, reported it in another period, or filed against the wrong GSTIN | Ask the supplier for the filing status. Do not claim until it appears |
| In GSTR-2B, not in register | Bill not booked, bill sent to another branch, or invoice not meant for you | Find the bill. If it is not yours, reject |
| Value difference | Rounding, a freight line, or a supplier typing error | Compare with the invoice copy and ask for an amendment |
| GSTIN mismatch | Wrong GSTIN in your vendor master, or the supplier used the wrong one | Fix the master first, then ask the supplier if the error is theirs |
| Invoice-number formatting | Dashes, slashes, spaces or leading zeros differ ("INV-0042" vs "INV/42") | Normalise both sides and re-match |
| Credit note | Not booked in your register, or the original invoice differs | Match to the original invoice, accept or hold pending |
Formatting differences are cheap to fix and wasteful to reject, so normalise before anyone opens IMS. Value differences can move credit even when small, so keep the evidence (invoice copy, supplier reply) with the line.
Who signs off
A routine with no named owner drifts. Three roles are enough for most teams:
- Preparer (accounts payable): runs steps 2 to 4 and records the cause for each variance.
- Reviewer (GST lead): decides IMS actions in step 5, particularly every rejection and every record held pending.
- Approver (finance controller): signs the variance report before GSTR-3B is filed, in line with the month-end checklist described in our workflows guide.
Small teams combine roles, but whoever decides a rejection should not be the only person who prepared the numbers. The record that matters is the signed report: reconciled value, claimed value, open items with causes, and the date of the GSTR-2B version used.
Common mistakes that cost credit
- Reconciling against the 14th draft and never recomputing. IMS actions taken afterwards are not in your statement, so your claim and your records drift apart.
- Leaving records on "no action". They are deemed accepted at generation. If a record was wrong, silence is an acceptance.
- Using pending as a parking lot. Pending items carry no credit and stay in IMS. Give each a chase date and an owner, and watch the Section 16(4) cut-off.
- Rejecting a formatting mismatch. It costs you credit and, for credit notes, can raise the supplier's liability for no good reason.
- Ignoring Rule 37 and Rule 37A. Rule 37 asks for a reversal of credit if the supplier is not paid within 180 days of the invoice date, with re-availing on payment. Rule 37A concerns suppliers who have not filed GSTR-3B by 30 September following the year end, and the GSTN IMS FAQ confirms such reversals flow into GSTR-2B. Confirm both with your CA. Payable ageing, covered in our procure-to-pay guide, is what makes Rule 37 manageable.
- Treating RCM, ICEGATE and ISD lines as IMS items. They arrive in GSTR-2B without an IMS step, so nobody reviews them.
- Leaving old periods open. Returns more than three years past their due date cannot be filed; the portal enforces this from the November 2025 tax period, so barred from 1 December 2025 (GST Council Newsletter, Issue 79).
- Booking bills that differ from the e-invoice. See our GST e-invoicing guide. TDS on the same bills is a separate track, covered in our TDS guide.
Where OpsGrids Finance fits
OpsGrids Finance covers GST returns and a diff against your books, and an IMS supplier reconciliation workflow, on a full ledger. The IMS workflow runs against a simulated GST portal today, so supplier records are not yet pulled from the portal and IMS actions are still taken on the portal itself. Invoices are append-only, so a correction is a new row that references the original.
Today Finance reconciles against its own purchase book, so purchase bills need to be booked there for the match to work. It does not match goods receipts. Notification rules can send events to people on WhatsApp or email. No software guarantees compliance: your data, portal availability and your CA's judgement still decide the outcome.
FAQ
When is GSTR-2B generated? A draft is generated on the 14th of each month. You can keep acting in IMS until you file GSTR-3B, but you must recompute GSTR-2B to see actions taken after the 14th.
What happens if I take no action in IMS? A record with no action is deemed accepted when GSTR-2B is generated. It then appears under ITC available and auto-populates GSTR-3B.
Should I reject or keep pending when an invoice does not match? If the cause is probably fixable, such as a missing filing or a formatting difference, keep it pending or re-match. Reject when the invoice is wrong and will not be corrected.
Which documents do not go through IMS? Reverse charge (RCM), ICEGATE and ISD documents flow straight to GSTR-2B. Review them separately in your routine.
Put the monthly routine on a ledger
If you want to see how this routine could run on your own purchase data, Talk to our team for a walkthrough.
Sources (checked 4 October 2026)
- GSTN FAQs and advisory on the Invoice Management System (tutorial.gst.gov.in)
- GSTN advisory on IMS and regenerating GSTR-2B, 8 October 2025 (gst.gov.in)
- GST Council Newsletter, Issue 79, October 2025 (gstcouncil.gov.in)
- CGST Act, 2017 (Sections 16(2)(aa), 16(4)) and CGST Rules, 2017 (Rules 37, 37A), as published by the CBIC (cbic.gov.in)