GST reconciliation, and why it now happens before you file
GST reconciliation is the invoice-by-invoice matching of three records that should agree and usually don't — your books (purchase register), the GST portal (GSTR-2B, generated from your IMS actions), and your bank (what you actually paid each supplier). It matters because your credit is only what your 2B supports (Section 16(2)(aa)), and because unpaid suppliers, unfiled suppliers and mismatched invoices each quietly reverse or block credit you thought you had.
"GST reconciliation" sounds like a month-end formality — tick the purchase register against the portal, file, move on. In 2026 it is neither monthly nor a formality. Your input tax credit is now decided by what your GSTR-2B contains before you file GSTR-3B, and 2B is built from actions you take invoice by invoice. This guide covers what you are actually matching, the four reconciliations that leak real money, and why the whole exercise moved upstream of the return.
What you are actually reconciling
Most people mean one thing by "GST reconciliation" — matching the purchase register in their books against the credit the portal shows. That is one comparison. In practice there are three records that all describe the same purchases and are almost never identical:
- Your books — the purchase register: every inward invoice you have recorded, with its GSTIN, value and tax.
- The portal — your GSTR-2B, an auto-generated statement of the credit available to you (Rule 60(7), CGST Rules) — monthly, or quarterly if you file under QRMP — now built from the Invoice Management System actions you take on each supplier document.
- Your bank — what you have actually paid each supplier, and when.
A filing utility or an ERP module typically reconciles the first two. The bank is usually left out — and that is the leg that carries two of the reversals below, because credit in GST is conditioned not just on holding an invoice but on paying for it.
Why GSTR-2B is the number that decides your credit
The single most important shift to internalise: your credit is not what your books say, and not what the ever-changing GSTR-2A shows. It is what your GSTR-2B contains. Section 16(2)(aa) of the CGST Act allows ITC on a supply only if the invoice has been furnished by the supplier and is communicated to you in GSTR-2B. If a purchase is in your books but not in your 2B, you cannot claim it this period — however genuine it is, and however clearly it sits in your ledger.
That is why reconciliation is now anchored to 2B specifically. Matching your books to GSTR-2A tells you what suppliers have filed; it does not tell you what you can claim. Only 2B does, and 2B is generated from your IMS positions on the monthly cut-off. The dashboard is upstream of the statement, and the statement is upstream of your return.
The four reconciliations that actually leak credit
"Does my books total match my 2B total?" is the reconciliation everyone runs and the one that catches the least. Bucket totals hide offsetting errors. The credit actually leaks through four invoice-level checks, each hanging off a different provision:
| Reconciliation | What you compare | What it catches | Provision |
|---|---|---|---|
| Books ↔ 2B | Purchase register vs GSTR-2B, line by line | Invoices you booked that the supplier never filed — no 2B entry, no credit | Sec 16(2)(aa) |
| Payment ↔ books | Bank payments vs invoice date | Suppliers unpaid past 180 days — credit must be reversed | Rule 37 (2nd proviso to Sec 16(2)) |
| Supplier filing ↔ 2B | Whether the supplier filed GSTR-3B, not just GSTR-1 | Credit that looks valid in 2B but is at risk because the supplier never paid the tax | Rule 37A |
| 3B ↔ 2B | ITC claimed in GSTR-3B vs available in 2B | An excess claim that can draw an automated DRC-01C intimation | Rule 88D |
Only the first is a "does it match" check. The other three are the ones a bucket comparison cannot see, and they are where the money is.
The bank leg almost nobody reconciles
Two of those four checks need data most GST tools never touch: your bank. Credit under GST is not final when you book the invoice — it is conditional on paying the supplier.
Under Rule 37 — which operationalises the second proviso to Section 16(2) — if you do not pay a supplier the invoice value plus tax within 180 days of the invoice date, the ITC you availed must be reversed (with interest), and re-availed only when you eventually pay. This runs on the full invoice value, including any amount you have retained. A large invoice with a retention held back can force a reversal on the unpaid portion once 180 days pass, even where the retention is contractually correct.
Catching this needs the payment matched to the invoice — which is a bank-to-books reconciliation, not a books-to-portal one. It is precisely the leg a filing suite is not built to run, and the reason a supplier-payment ageing that is accurate to the invoice is worth more than another 2B match.
Why the whole exercise moved before you file
Reconciliation used to be something you did after filing, to prepare for the annual return. It has moved to the front for two reasons, both live today.
First, IMS. A supplier document you never action is deemed accepted into your GSTR-2B. Across a few hundred vendors, that means duplicate, overstated or wrong-GSTIN invoices flow into your credit unless you catch them before the cut-off — reconciliation is now the thing that decides what your 2B contains, not a check you run on it afterwards.
Second, the DRC-01C intimation. If the ITC you claim in GSTR-3B runs ahead of your 2B beyond the portal's threshold, the system issues an automated notice under Rule 88D and gives you seven days to pay or explain, or your next GSTR-1 is blocked.
Why this is hard to do by hand
At a handful of invoices, all of this is a coffee-break task. Across a few hundred vendors and multiple GSTINs, four invoice-level reconciliations against three separate systems every month is painful to do manually — and a single overlooked line either loses real credit or invites a notice. Sampling creeps in, and sampling is exactly where credit leaks.
How Recoup does it
Recoup connects read-only to your bank, your books (Zoho Books or Tally) and the GST portal, and runs all four reconciliations at once — invoice by invoice, not bucket by bucket. Instead of a total that says "₹14 lakh unmatched," you get the exceptions named: the invoice a supplier never filed, the payment now past 180 days, the supplier who filed GSTR-1 but not GSTR-3B, and the 3B-vs-2B gap that would draw a notice. Because it reads the bank, it can track the Rule 37 clock and tie each payment to its invoice — the reconciliation a filing suite cannot run. IMS gives you the buttons; Recoup tells you which line needs which one.
Keep reading
GSTR-2B, IMS & hard-locking
How your 2B is now built from IMS actions, and why that moved reconciliation before filing.
The supplier who hasn't filed
What to do when a genuine invoice never reaches your 2B because the vendor didn't file.
The DRC-01C 7-day playbook
When your 3B ITC and 2B don't agree — the notice, the clock, and the reply.
This guide is general information, not tax advice. GST positions change; verify every provision, threshold and date against the current CGST Act, Rules, CBIC circulars and the GST portal before acting.
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