How to Do GST Reconciliation: A Consultant's Guide

A step-by-step guide for tax consultants: match GSTR-2B with GSTR-3B, catch blocked credits under Sec. 17(5), test rates against the date of supply, and answer a DRC-01C before it blocks your next filing.

What is GST reconciliation?

GST reconciliation is the process of comparing the invoices you have recorded in your books against the returns filed (or available) on the GST portal. The three main checkpoints are:

**GSTR-1 vs sales register** — ensure every outward supply is reported under the right tax head and at the rate notified on the date of supply.

**GSTR-2B vs purchase register** — confirm that every input tax credit (ITC) you intend to claim is actually reflected in the portal-generated statement.

**GSTR-3B vs GSTR-1 and GSTR-2B** — the monthly summary return must not claim more ITC, or understate more liability, than the underlying returns support.

Why reconciliation matters for consultants

A small mismatch that slips through becomes a bigger problem later:

**Interest and late fees** if excess ITC is reversed after filing.

**Portal intimations** — a DRC-01C under Rule 88D where ITC claimed in GSTR-3B exceeds what GSTR-2B supports, or a DRC-01B where liability declared in GSTR-1 exceeds tax paid in GSTR-3B.

**Blocked filing** — an unanswered DRC-01C stops the next GSTR-1 or IFF from being filed.

**Credit lost for good** under Sec. 16(4) once the November availment deadline passes.

**Client trust erosion** when the consultant discovers the error after the client has already paid tax or claimed refund.

Reconciliation is not just a compliance step — it is the quality gate that protects both the taxpayer and the practice.

A practical step-by-step workflow

Step 1: Fix the period to the Indian financial year

Always reconcile in FY chunks (April–March). Monthly or quarterly views are useful, but the annual reconciliation catches carry-forward mismatches that monthly checks miss.

Step 2: Download the source data

You need:

GSTR-1 JSON / Excel for outward supplies.

GSTR-2B for the period (this is the authoritative ITC statement).

GSTR-3B summary for the same period.

The client’s sales and purchase register in Excel or CSV.

Step 3: Normalise invoice keys

Match on a composite key: **GSTIN of counterparty + invoice number + invoice date + taxable value + tax rate**. Invoice numbers alone are not reliable because suppliers reuse series.

Step 4: Run the four-way match

|-------|----------|----------|--------------------------|

On rates, note that the slab structure changed with effect from **22 September 2025** — broadly 5% and 18%, with a 40% rate on select goods, replacing the earlier structure that included 12% and 28%. FY 2025-26 therefore spans two regimes, so every rate test must key off the date of supply rather than one fixed slab list.

Step 5: Flag exceptions by law

Every exception should be tied to the section or rule it breaches. The ones that matter most:

**Sec. 17(5)** — blocked credits (motor cars, construction, food, club memberships).

**Sec. 16(2)(a) and (b)** — a valid tax invoice or debit note, and receipt of the goods or services.

**Sec. 16(2)(aa) r/w Rule 36** — credit only where the supplier has furnished the invoice in GSTR-1/IFF and it is communicated in GSTR-2B. Provisional credit beyond GSTR-2B ended on **1 January 2022**, so there is no percentage allowance any more — the old Rule 36(4) tolerance (20%, then 10%, then 5%) no longer applies, and the earlier matching provisions in Sections 42, 43 and 43A were omitted after Budget 2022.

**Sec. 16(2)(c)** — tax charged must actually have been paid to the Government.

**Sec. 16(4)** — credit cannot be availed after 30 November following the end of the financial year the document relates to.

**Rule 88D** — where the 3B-versus-2B ITC difference crosses the notified tolerance, the portal issues a DRC-01C with **seven days** to reply in Part B; non-response blocks the next GSTR-1/IFF.

Step 6: Prepare the advisory

Document each exception with the rupee impact, the clause, and the corrective journal entry. Share this with the client before filing so they can approve the reversal or amendment.

Common mistakes to avoid

**Reconciling only at invoice number level** — always include value, date and GSTIN.

**Applying a fixed slab list across the year** — after 22 September 2025 the valid rates depend on the date of supply.

**Assuming a percentage cushion over GSTR-2B** — provisional credit ended on 1 January 2022; if it is not in 2B, it is not available yet.

**Ignoring amendments** — amended invoices can create double counting if the original is not reversed.

**Letting Sec. 16(4) run out** — a supplier chase that drifts past 30 November loses the credit permanently.

**Leaving a DRC-01C unanswered** — seven days, and the next GSTR-1/IFF is blocked until Part B is filed.

**Mixing tax periods** — reconcile within the same return period; do not use book dates blindly.

**Forgetting reverse charge** — RCM entries must be matched separately because the supplier invoice does not appear in 2B as a credit.

Speed this up with Pinnacle GST360

Pinnacle GST360 automates the manual steps above:

Connects to the GST portal through Alankit, a GSTN-licensed GST Suvidha Provider, and pulls GSTR-1, GSTR-2A, GSTR-2B and GSTR-3B.

Runs the four-way match automatically and ranks exceptions by rupee impact.

Cites the exact section, rule or notification for every flag, tested against the law in force on the date of supply, with the review date shown on screen and in every export. The engine that finds and cites is deterministic — citations are never generated by a language model.

Flags DRC-01C exposure and time-barred credit under Sec. 16(4) before GSTR-3B is filed.

Exports a client-ready PDF advisory and a working CSV in one click.

Lets firm owners and admins prepare GSTR-1 and GSTR-3B, including nil returns, from reconciled books; dry-run before submission, validate with the portal, approve, then file by EVC after client authorisation.

Keeps the ARN, filed figures and a record of who prepared, approved and filed the return.

You can also test the engine without signing up using the free pre-filing simulator.

How to do GST reconciliationlike a pro