You run the match on the 14th and get a list of unmatched invoices. The instinct is to send that list to the suppliers. That is how accounts teams end up apologising to a vendor on the 18th for a GSTIN they mistyped themselves. Before any email goes out, every exception needs a label: is the mistake in our books, in our portal actions, or in what the supplier reported?
This page is one part of our GSTR-2B reconciliation guide, which shows how the whole process fits together.
The legal reason the label matters is simple. ITC can be claimed only for invoices that the supplier furnished in GSTR-1 and that were communicated to you in GSTR-2B (Section 16(2)(aa) and Rule 36(4)). An exception that is your own typing error costs you nothing once you fix it. An exception that is the supplier’s omission costs you cash until they act.
The twelve errors in one table
| Error | Usual cause | How it shows up | Fix | Owner |
|---|---|---|---|---|
| 1. Wrong supplier GSTIN | Typo, old GSTIN, or the supplier’s other state registration used in books | Invoice sits in “in books, missing from 2B” while an invoice for the same amount sits in “in 2B, not in books” under another GSTIN | Correct the GSTIN in the register from the invoice copy and re-run | You |
| 2. Invoice-number format | Slash vs hyphen, leading zeros, financial-year prefix, spaces or a # typed into the register | Same pair as error 1, but the GSTIN is the same and only the number differs | Normalise the number; see fuzzy invoice matching | You |
| 3. Small value difference | Rounding done line by line in one system and on the invoice total in the other | Tax differs by a rupee or so on an otherwise identical invoice | Treat as matched within your tolerance; see round-off mismatches | You |
| 4. Large value difference | Wrong tax rate, freight or discount treated differently, supplier keying error | Same invoice, tax figures differ by a real amount | Check the invoice copy. Claim the lower supportable figure, never above 2B, and ask the supplier to correct their record | Supplier |
| 5. Reported in a later month | Supplier filed GSTR-1 after your GSTR-2B was generated | Invoice missing this month, present next month | Do not claim now; claim when it appears, inside the Section 16(4) limit. See the time-limit playbook | Supplier |
| 6. Kept Pending in IMS | Someone on your team left the record on Pending in IMS | Supplier says it is filed; it is not in your 2B | Accept or reject, then recompute GSTR-2B before filing GSTR-3B. See the IMS decision tree | You |
| 7. Supplier has not filed | GSTR-1 not filed, or the invoice was left out of it | Nothing under that GSTIN in 2B for the month | Follow up in writing; see supplier not filing GSTR-1 and the payment hold SOP | Supplier |
| 8. Credit note not matched | Supplier issued a credit note but has not reported it, or you have not booked it | Note in books but not in the CDNR section of 2B, or the reverse | Confirm the note with the supplier, check its IMS action. See credit notes and IMS | Both |
| 9. Reverse-charge entries | Tax on the purchase is paid by you under reverse charge, not charged by the supplier | The entry can sit unmatched in either direction, because it does not follow the normal supplier-charged-tax pattern | Reconcile these on a separate sheet; see RCM matching for where they sit in GSTR-2B | You |
| 10. Duplicate entry | One bill booked twice, for example once on goods receipt and again on the supplier’s invoice | Two rows with the same supplier, date and amount; ITC in books is double | Keep one entry; claim the credit once | You |
| 11. Amended invoice | Supplier amended the invoice after reporting it | Original in your books, amendment in the B2BA section of 2B | Book the amended values; see amended invoices and GSTR-1A | Both |
| 12. Booked under the wrong GSTIN of yours | Purchase entered in one branch or state registration, invoice raised on another | Missing in this GSTIN’s 2B, present in another GSTIN’s 2B | Reconcile against every GSTIN’s 2B; see multi-GSTIN reconciliation | You |
Errors that look like one thing and are another
Missing from 2B: is it error 1, 2, 5, 6, 7 or 12?
“In books, missing from 2B” is the least informative label in reconciliation, because six different errors produce it. Work through them in this order, cheapest check first: first look for the same amount in the “in 2B, not in books” list (errors 1 and 2); then check the invoice under your other GSTINs (error 12); then open IMS for the supplier (error 6); and only then write to the supplier (errors 5 and 7). Two invoices from the same supplier for the same amount in one month are the reason to check the date as well as the amount before you pair them.
Invoice numbers: what the rules allow
Rule 46(b) of the CGST Rules says an invoice number is a consecutive serial number of not more than sixteen characters, made of alphabets, numerals, and the hyphen and slash, and unique for a financial year. That gives you two practical tests. A number in your register containing a space, hash or backslash was almost certainly typed differently from the invoice. And two invoices with the same number from the same supplier in the same financial year should not exist; if your books show that, one of them is a duplicate (error 10) or a keying mistake.
Value differences: rounding or real?
Decide your own tolerance and write it down, so that the team does not argue invoice by invoice. The tool on this site flags a value mismatch when the tax differs by more than ₹1. A rounding difference on a ₹9,000 invoice is noise. A ₹360 difference on a ₹18,000 tax figure is not; it is usually a wrong rate or a supplier keying error and is worth a query.
Never close a gap by claiming the higher number. Rule 36(4) allows ITC only on invoices communicated in GSTR-2B. If ITC claimed in GSTR-3B exceeds what 2B shows beyond the pre-defined limit, a Form DRC-01C intimation follows, and interest at 18% a year applies where ITC is wrongly availed and utilised. When two figures disagree, claim the lower one you can support.
Worked example: nine exceptions, three owners
A distribution business reconciles its August 2026 register on 14 September 2026, the day GSTR-2B is generated. After matching, nine exceptions remain. The “ITC affected” column is the tax figure hanging on each one.
| # | Exception | Error type | ITC affected | Owner |
|---|---|---|---|---|
| 1 | Invoice 0921: GSTIN typed with one wrong digit | Wrong GSTIN (1) | ₹8,100 | You |
| 2 | AB/26-27/0144 in books, 144 in 2B | Number format (2) | ₹15,300 | You |
| 3 | Credit note CN-88 reported by supplier, not booked | Credit note (8) | ₹6,300 | You |
| 4 | Tax ₹18,000 in books, ₹17,640 in 2B | Large value difference (4) | ₹360 | Supplier |
| 5 | Record left Pending on IMS dashboard | IMS Pending (6) | ₹32,400 | You |
| 6 | Supplier has filed nothing for August | Not filed (7) | ₹47,700 | Supplier |
| 7 | One freight bill booked twice | Duplicate (10) | ₹11,250 | You |
| 8 | Purchase on which the tax is paid by you under reverse charge | Reverse charge (9) | ₹9,000 | You |
| 9 | Supplier says GSTR-1 for August filed on 16 September | Reported later (5) | ₹21,600 | Supplier |
| Total | ₹1,52,010 |
Grouped by owner: rows 1, 2, 3, 7 and 8 are the business’s own bookkeeping and add up to ₹49,950 (8,100 + 15,300 + 6,300 + 11,250 + 9,000). Row 5 is an IMS action worth ₹32,400. Rows 4, 6 and 9 depend on the supplier and add up to ₹69,660 (360 + 47,700 + 21,600). The three groups total ₹1,52,010.
Notice what the split does to the supplier list. Sent as it stood, the exception list would have gone to suppliers with all nine rows and ₹1,52,010 on it. After the business fixes its own rows and accepts the IMS record, three rows remain, and the ₹47,700 in row 6 is the only one that needs escalation. Row 9 needs only a watch on new GSTR-2B statements: the supplier has filed, but the invoice will not be in the 14 September statement, and it can be claimed once it appears provided the Section 16(4) limit is open.
The order to fix things in
- Books first. Correct GSTINs, invoice numbers, duplicates and reverse-charge entries, then re-run the match. Every row you clear here is a row you do not have to explain to a supplier.
- IMS second. Decide accept or reject on anything you left Pending, then recompute GSTR-2B before you file GSTR-3B. Records kept Pending do not become part of GSTR-2B or GSTR-3B, so this is where blocked credit is released.
- Supplier list third. Send one message per supplier with all their invoices, not one per invoice. The 14th to 20th timeline shows how to schedule this so answers arrive before your GSTR-3B is due on the 20th.
- Timing list last. Anything reported after the 14th goes on a carry-forward sheet with its invoice date, so that nothing drifts past the Section 16(4) date: 30 November following the end of the invoice’s financial year, or the annual return date if that is earlier.
Common mistake: editing the downloaded GSTR-2B to make a row match. The 2B file is your evidence of what suppliers reported. Change your own register, or the supplier’s record through the supplier, and leave the portal file as it came.
Sort your exceptions before you chase anyone
The tool puts each invoice into a bucket: matched, value mismatch, in books but missing from 2B, in 2B but not in books, or IMS Pending, and lists duplicates in your register separately (counted once), so you can clear the errors that are yours first. It cannot read your live IMS dashboard, so confirm the Pending records there. Your GSTR-2B and purchase register files are read in your browser and never uploaded to any server.
Related guides
- GSTR-2B reconciliation guide: the complete guide to ITC matching
- how to find GSTR-2B mismatches: finding them in three passes: totals, supplier, invoice
- invoice missing in GSTR-2B: what to do when an invoice is in your books but not in 2B
- duplicate invoice in GSTR-2B: spotting and fixing duplicates
- How accountants can automate GSTR-2B reconciliation
- GSTR-2B rejected invoices fix: how to resolve portal errors
- GSTR-2B vendor wise reconciliation guide
- GSTR-2B reconciliation for large businesses
- How to use a GSTR-2B reconciliation tool
Last checked: 30 September 2026. Sources: Notification 39/2021-Central Tax (Section 16(2)(aa)), Notification 40/2021-Central Tax (Rule 36(4)), CGST Rules, Rule 46, CBIC Circular 237/31/2024-GST (Section 16(4)), GSTN IMS FAQ, GSTN FAQ on 2B tables, GSTN advisory on DRC-01C, GSTN GSTR-3B user guide, Notification 13/2017-Central Tax (interest rate).