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), fix rate mismatches, and avoid GST notices.

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 rate.

**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.

**GST notices** such as DRC-01 for difference between 3B and 2B.

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

**Cash-flow shock** when ineligible credits are disallowed in a later period.

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

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

Step 5: Flag exceptions by law

Every exception should be tied to the section or rule it breaches. Common ones include:

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

**Sec. 16(2)** — ITC without a valid tax invoice or debit note.

**Sec. 42 / 43** — matched, unmatched and pending ITC rules.

**Rule 36(4)** — ITC restricted to 120% of eligible reflected in GSTR-2B (where applicable).

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.

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

**Claiming ITC before 2B reflects it** — unless the client wants to take the 120% rule position explicitly.

**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 a licensed GSP and pulls GSTR-1, 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.

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

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

How to do GST reconciliationlike a pro