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To fix a GST return mismatch, first identify whether it concerns outward liability reported in GSTR-1 versus GSTR-3B, input tax credit (ITC), an incorrect or missing GSTR-1 entry, a portal upload or validation error, or a filing dependency. Each has a different correction or response route; a difference in figures alone does not mean you should pay or reverse tax.
This guide covers Indian GST returns. Portal rules and deadlines can change, so check the live return tile and any period-specific government notification before filing.
Identify what is mismatching before changing a return
Start with the GSTIN and tax period, then identify the two records that disagree. Keep outward-supply liability separate from recipient ITC: the portal uses distinct compliance processes for these issues.
| Problem | What to compare | Likely route |
|---|---|---|
| GSTR-1 and GSTR-3B liability mismatch | Outward supplies and tax reported in GSTR-1 against liability reported or discharged in GSTR-3B | Reconcile first; if the portal issues an intimation, follow DRC-01B. |
| ITC mismatch | Your ITC records and claim against supplier-reported information and your return position | Check the underlying records; if intimated, follow DRC-01C. |
| GSTR-1 entry error or omission | Filed invoice details against books and source documents | Consider same-period GSTR-1A if it is available and GSTR-3B for that period is not yet filed. |
| Portal validation or upload error | Table totals, required fields, uploaded data, and any error report | Correct the data or upload; do not assume the tax liability itself is wrong. |
| Return tile blocked | Required earlier-period and same-period filings | Check filing dependencies before treating the block as a new mismatch. |
The GST Portal’s GSTR-1 guidance and separate FAQs for DRC-01B and DRC-01C describe these different workflows.
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Reconcile the records behind the difference
- Open the returns for the same period. View or download the filed GSTR-1 and GSTR-3B, plus the relevant recipient statement if you are investigating ITC.
- Match invoice-level details against your books. Check invoice number and date, recipient GSTIN, place or state of supply where relevant, taxable value, tax rate and tax amounts. Include credit and debit notes and amendments.
- Check whether the return summary agrees with its underlying tables. The portal’s GSTR-1 creation guidance describes warnings when Table 12 totals do not match related supply tables and identifies cases where Table 13 is mandatory.
- Inspect uploads and error reports. If you used the offline tool, download any generated error report and correct the listed records. The portal’s known-issues guidance says a GSTR-1 “Data mismatch” error can occur when no data or incomplete data was uploaded, and recommends uploading complete data.
- Check for duplicate invoices and invalid recipient details. GSTR-1 guidance says duplicate supply invoices are not accepted and recommends checking recipient GSTIN validity.
Correct the record that is actually wrong, rather than changing a summary total merely to make it agree. Keep outward-liability reconciliation separate from ITC reconciliation.
Choose the correction route based on return status
GSTR-1 is filed, but same-period GSTR-3B is not
GSTR-1A is an optional facility available once for a tax period. It can be used to amend records already reported in that period’s GSTR-1 or add omitted records, before filing that period’s GSTR-3B. The portal says it becomes available after GSTR-1 is filed or its due date has passed, whichever is later. Changes made through GSTR-1A are auto-populated into the supplier’s GSTR-3B.
For a recipient, supplies declared or amended through a supplier’s GSTR-1A appear as ITC in the next tax period’s GSTR-2B, not that same period’s statement. This timing can account for an apparent month-to-month difference.
GSTR-3B for the period has already been filed
GSTR-1A is not a way to revise an already-filed GSTR-3B. For an error outside the GSTR-1A window, check the applicable subsequent-return amendment rules and cutoff for the period. The portal states that additions or amendments to previous-financial-year GSTR-1 invoices are not allowed after 30 November of the following financial year. See the CBIC sectoral FAQs and current portal guidance for the applicable rules; do not assume every correction can be made in the same way.
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GSTR-1 or GSTR-3B is still in draft
Before filing, correct the source entry or upload data, resolve table validations, and regenerate or review the return summary. If a prior return is unfiled, check whether it is preventing the current return from proceeding.
Respond to a DRC-01B or DRC-01C intimation
DRC-01B: GSTR-1 versus GSTR-3B liability
The portal FAQ says monthly filers may receive DRC-01B after monthly GSTR-3B, and QRMP filers after quarterly GSTR-3B, as applicable. The portal path is Services > Returns > Return Compliance > Liability Mismatch DRC-01B. Read the intimation and reconcile the stated period and amount before deciding how to respond; a mismatch by itself does not establish what is payable.
If your response uses DRC-03 payment details, the portal FAQ says to verify that the ARN belongs to the same GSTIN and relevant period, that the DRC-03 was filed on or after DRC-01B Part A, and that the payment cause is “Liability mismatch – GSTR-1 to GSTR-3B.” The FAQ says that after Part B is filed, GSTR-1/IFF can be filed instantly. If the filing screen remains blocked, it suggests logging out and back in after a few minutes.
DRC-01C: ITC mismatch
DRC-01C is the portal’s ITC mismatch intimation. Its FAQ describes Part B filing according to the taxpayer’s monthly or quarterly GSTR-3B frequency. If responding with DRC-03 details, check the GSTIN, ARN, payment cause, issue timing and tax-period alignment against the actual intimation. Do not use an ARN from another GSTIN or period.
Neither form’s FAQ determines the correct tax treatment for every discrepancy. Examine the notice, source records and applicable rules before claiming, reversing or paying an amount.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Check due dates and filing dependencies
The GST Portal says GSTR-1 is generally due on the 11th day of the succeeding month for monthly filers, or the 13th day of the month following the quarter for quarterly filers, unless a government notification extends the date. Confirm the live portal tile and any period-specific notification rather than relying on a generic calendar.
Portal guidance also describes dependencies: earlier returns may need to be filed before later GSTR-1 filings, and the same period’s GSTR-1 must be filed before its GSTR-3B. Requirements depend on the form, period and filing frequency, so inspect the specific blocked tile and its prerequisites before retrying.
Keep records that explain the correction
Retain the reconciliation workings, source invoices, filed return PDFs, portal intimations, upload error reports, relevant payment ARN and final acknowledgement. These records help show which entry was corrected and how a response relates to the GSTIN and period.
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