• GST Reconciliation

GST Reconciliation: A Practical Guide for 2026

GST reconciliation is the monthly discipline of proving that what you filed on the GST portal, what you paid, and what your books say all agree. This page explains the two core checks — GSTR-1 vs GSTR-3B and GSTR-2B vs the purchase register — and gives you a repeatable month-end workflow, with links to the deep-dive articles for each step.

What GST reconciliation actually means

A registered business files several GST returns each period, and each one is a different view of the same transactions. GSTR-1 reports outward supplies. GSTR-3B is the summary return where tax is actually paid and Input Tax Credit is claimed. GSTR-2B is a system-generated statement of the credit available from suppliers. Reconciliation is the work of lining these up against each other and against the books, and explaining every difference before the return is filed.

Done monthly, it catches a missed invoice or a wrong GSTIN while the trail is still fresh. Skipped until year-end, the same differences compound into a single large gap in GSTR-9 that is expensive to investigate and hard to defend in an audit.

The two core checks

1. GSTR-1 vs GSTR-3B — outward liability

The tax liability you declare invoice-by-invoice in GSTR-1 should equal the liability you pay in the summary GSTR-3B for the same period. Differences are almost always timing (an invoice in one month's GSTR-1 but the next month's GSTR-3B), amendments, credit notes, or reverse-charge entries recorded in one return but not the other. From 2026, GSTR-3B is progressively hard-locked to the GSTR-1 figures, so this check has to be clean before you file, not after.

2. GSTR-2B vs the purchase register — Input Tax Credit

Every purchase invoice in your books should appear in GSTR-2B, and every invoice in GSTR-2B should exist in your books. Credit for anything that is in the register but not in GSTR-2B cannot be claimed this period. Credit for anything in GSTR-2B but not the register is either a missed entry or an invoice wrongly issued to your GSTIN — and the second case needs an Invoice Management System rejection before the statement is finalised.

Every reconciliation is only as good as its inputs. GST Reco Pro converts GSTR-1 and GSTR-3B PDFs into clean, column-matched Excel sheets entirely in your browser — no uploads — so the same matching logic runs identically for every client, every month.

Convert GSTR-1 and GSTR-3B PDFs to Excel →

A five-step month-end workflow

Assemble the source documents. Download GSTR-1 and GSTR-3B for the period, the GSTR-2B statement, and the books-side purchase and sales registers. Convert the portal PDFs to Excel so every statement is in the same tabular shape.
Reconcile GSTR-1 against GSTR-3B. Match outward tax liability declared in GSTR-1 to the liability paid through GSTR-3B for the same period. Explain every difference as a timing entry, an amendment, or a genuine short/excess payment.
Reconcile GSTR-2B against the purchase register. Match each purchase invoice to GSTR-2B by GSTIN and invoice number, then by taxable value and tax amount. Split the exceptions into 'in books, not in 2B' and 'in 2B, not in books'.
Clear the Invoice Management System. For every 'in books, not in 2B' item, check the IMS dashboard first. Accept genuine invoices, reject invoices wrongly issued to your GSTIN, and chase suppliers for anything still unfiled.
Lock the numbers and file. Once GSTR-1 vs GSTR-3B and GSTR-2B vs books both tie out, lock the ITC and liability figures, file GSTR-3B, and archive the working papers for the annual return and any future audit.

GSTR-2A, GSTR-2B and IMS in 2026

GSTR-2A is dynamic — it keeps updating as suppliers file late. GSTR-2B is static — generated once per period and then frozen — and it is the statement ITC eligibility is tested against. From April 2026 the Invoice Management System sits between supplier filings and GSTR-2B: invoices you accept flow in, invoices you reject or leave pending do not. Reconciliation now has to account for the IMS decision layer, not just the raw supplier data.

Deep dives

Each step above has a dedicated article with worked examples, checklists, and the underlying law.

GSTR-2A vs GSTR-2B: The Difference That Decides Your Input Tax Credit in 2026
GSTR-2A is a live, ever-changing record; GSTR-2B is a frozen monthly statement. Since 1 January 2022 only GSTR-2B governs how much Input Tax Credit a business can lawfully claim, and the 2026 IMS regime has widened the gap between the two.
Input Tax Credit Under Section 16: Conditions, Time Limits, and the 30 November Deadline
Section 16 of the CGST Act sets four cumulative conditions for claiming ITC and a hard outer time limit. For FY 2025-26, any credit not claimed by 30 November 2026 is permanently lost — and in 2026 the portal enforces that automatically.
GSTR-3B Hard-Locking in 2026: When the Numbers Stop Being Editable and What to Do About It
From the July 2025 tax period the outward liability in GSTR-3B is auto-populated from GSTR-1 and cannot be edited on the portal. From July 2026 the same logic reaches Table 4A ITC. Corrections now happen upstream, before the return, or not at all.
The Month-End GST Reconciliation Workflow: A Step-by-Step Close Checklist for CA Firms
Monthly GST close is not one reconciliation but four, run in a specific order against deadlines that no longer forgive a late catch. This is the sequence a firm can standardise across every client and every GSTIN.
Turning GSTR-2B and GSTR-3B Into a Working ITC Match: A Practical Excel Workflow
The portal gives you GSTR-2B as JSON and GSTR-3B as PDF. Neither is a reconciliation. This is how to get both into a single Excel workbook and run an invoice-level ITC match without retyping a line.
GSTR-2B Reconciliation Checklist: How to Stop ITC Leakage Every Month
GSTR-2B reconciliation remains the single most time-consuming step in the monthly compliance cycle. A disciplined monthly checklist prevents small mismatches from becoming lost ITC.
GSTR-1 vs GSTR-3B Mismatch: Common Causes, Rule 88C Notices, and How to Reconcile Before It's Too Late
A mismatch between GSTR-1 outward supply figures and GSTR-3B tax payment can trigger a Rule 88C notice within days of filing. Here's what causes the mismatch and how to reconcile proactively.
Invoice Management System (IMS) Under GST: A Practical Workflow for Accepting, Rejecting, and Managing ITC
IMS puts every supplier-reported invoice on a single dashboard where recipients accept, reject, or leave it pending — directly shaping what lands in GSTR-2B. Here's how to build a monthly action workflow.
Multi-GSTIN Reconciliation: How CA Firms Standardize GST Compliance Across Branches and States
Firms managing multiple GSTINs for a single client — or for their own multi-branch practice — face a structural choice between centralized and decentralized compliance. Here's a framework for getting it right.
GSTR-9 and GSTR-9C Annual Return: Turnover Limits, Due Dates, and a Pre-Filing Checklist
GSTR-9 applies above ₹2 crore turnover and GSTR-9C above ₹5 crore, both due within nine months of the financial year end. Here's what to reconcile before the filing window opens.

Frequently Asked Questions

What is GST reconciliation?

GST reconciliation is the process of matching the GST data a business has filed on the GST portal against its own books of account, and matching the different portal statements against each other. The two core checks are GSTR-1 versus GSTR-3B (outward liability declared versus paid) and GSTR-2B versus the purchase register (Input Tax Credit available versus claimed).

Which statement is used to claim Input Tax Credit — GSTR-2A or GSTR-2B?

GSTR-2B. Since 1 January 2022, Section 16(2)(aa) of the CGST Act ties eligible ITC to the static, auto-generated GSTR-2B statement. GSTR-2A is a dynamic reference document used mainly to support the annual return.

How often should GST reconciliation be done?

Every month, before GSTR-3B is filed. A monthly reconciliation keeps mismatches small and traceable; waiting until the annual return turns a year of small timing differences into one large, hard-to-explain gap.

Does GST Reco Pro auto-match GSTR-2B against the purchase register?

Not yet. GST Reco Pro today converts GSTR-1, GSTR-3B, and TDS Challan PDFs into clean, column-matched Excel sheets entirely in your browser, so you can run the matching in Excel with consistent inputs. Automated GSTR-2B to purchase-register matching is on the roadmap.

What causes most GSTR-1 vs GSTR-3B mismatches?

Timing — an invoice reported in GSTR-1 in one month but accounted for tax payment in GSTR-3B of another — plus amendments, credit notes, and reverse-charge entries that are recorded in one return but not the other.