GSTR-1 and GSTR-3B reconciliation

Compare the same liability, not unrelated totals

GSTR-1 contains outward-supply details while GSTR-3B includes summary liability and credit information. Comparing total invoice value with net cash tax paid does not test whether outward tax was reported correctly. Separate taxable value, tax liability and the method of discharging that liability.

Work by GSTIN, return period and tax head. Keep reverse-charge inward liabilities and other categories separate from outward supplies where they do not belong in the same comparison. Document the table mapping used in the reconciliation.

Freeze the source records

Download the relevant filed or draft return data and retain the extraction date and status. Include GSTR-1A information where applicable, earlier-period amendments and the books used for the close. A draft return should not be labelled as a filed source.

The GST portal’s GSTR-1 guidance describes auto-population from e-invoices and the effect of GSTR-1A changes on GSTR-3B. Review the underlying records even where figures are populated automatically; automation does not establish the correct transaction classification.

Prepare the reconciliation bridge

• Start with the sales register and tax ledgers for the GSTIN and period.
• Map invoices, debit notes and credit notes to the relevant outward-supply categories.
• Separate current-period transactions from earlier-period amendments.
• Compare taxable values and IGST, CGST, SGST or UTGST and cess separately.
• Identify differences between books, GSTR-1 or GSTR-1A and the corresponding GSTR-3B liability.
• Record the explanation, evidence, proposed correction and responsible owner for each difference.

Investigate common differences

Check missing or duplicate invoices, incorrect customer registration details, tax-head errors, credit-note timing, advances and their adjustments, export treatment and amendments. Do not group unexplained amounts into a permanent “rounding” line.

For example, an invoice reported as an interstate supply in GSTR-1 may have been posted as intrastate in the books. The total tax can appear to match while the tax heads differ. Review the place-of-supply facts, identify the correct treatment and assess the permitted correction and payment process.

Choose the correction route before filing

For current-period errors, the GST portal’s GSTR-1A FAQ says the optional facility opens after GSTR-1 is filed or its due date, whichever is later. It can be filed once for that period, before the corresponding GSTR-3B is filed. Gather all eligible corrections before using it; a filed GSTR-3B closes this route for that period. Earlier-period errors require assessment of the applicable amendment route and time limits.

The FAQ distinguishes the supplier’s liability from the recipient’s statement: GSTR-1A changes flow into the supplier’s GSTR-3B for the same period, while supplies added or amended appear in the recipient’s next-period GSTR-2B. Record that timing difference when investigating a customer’s missing-invoice query.

Keep the original data and a clear record of the correction. Do not alter a ledger simply to make it equal a mistaken return, or change a return figure without resolving the underlying transaction. Assess any additional liability and interest separately.

Reconcile payment after liability

Once the liability is agreed, reconcile its discharge to the relevant cash and credit ledger entries and filing evidence. A cash deposit is not by itself proof that a liability has been offset or the return filed. Retain the filed return and acknowledgement with the reconciliation.

Carry unresolved items into a dated tracker with an owner and next action. At the following close, confirm that the planned amendment or payment actually happened instead of treating an explanatory note as completion.

Build a repeatable monthly close

Use a consistent invoice-level export, table mapping and exception log. Review cumulative differences across periods so that timing explanations reverse as expected. Keep access to customer and transaction data restricted to the people completing the reconciliation.

Bring the sales register, tax ledgers, GSTR-1 and GSTR-1A data where applicable, GSTR-3B, credit-note records and payment evidence to Kosha.Services. We can help establish the bridge, investigate exceptions and coordinate the correction workflow.