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GST · Registration & returnsGSTR-1 vs GSTR-3B: reconciliation with examples
GSTR-1 reports what you sold; GSTR-3B is where you pay tax. When the two do not match, the GST system sends automated notices and can block your next GSTR-1. Here is how to reconcile them, correct differences and use GSTR-1A.
Every regular taxpayer files two main returns: GSTR-1 (statement of outward supplies, Section 37) and GSTR-3B (summary return with tax payment, Section 39). In theory, tax in GSTR-3B Table 3.1 should equal tax on supplies reported in GSTR-1. In practice, mismatches are common and are now actively monitored.
Why mismatches happen
| Cause | Example |
|---|---|
| Invoice missed in GSTR-1 | Last-day invoice not uploaded |
| Invoice reported in GSTR-1 but tax not paid in 3B | Cash crunch, deliberate deferral |
| Different months | Invoice dated 31 March in GSTR-1 of March, but tax paid in April 3B |
| Credit notes | Reported in GSTR-1 but not reduced in 3B, or vice versa |
| Advances received | Tax paid in 3B on advances (services) but invoice reported later |
| Amendments | Changes in GSTR-1 of later months for earlier invoices |
| Rate / POS errors | IGST shown as CGST/SGST |
The system controls
- Auto-population: GSTR-3B Table 3 is auto-filled from GSTR-1/IFF/1A, and the portal increasingly locks these values.
- GSTR-1A: lets you correct GSTR-1 of the same period before filing GSTR-3B.
- DRC-01B (Rule 88C): if GSTR-1 liability exceeds GSTR-3B by more than the prescribed limit (₹25 lakh or 20%, as notified), an intimation is sent. Reply with payment (DRC-03) or explanation within 7 days, or the next GSTR-1 is blocked.
- ASMT-10: officers use mismatch data for scrutiny – see ASMT-10 guide.
Month-wise reconciliation format
| Month | GSTR-1 taxable value | GSTR-1 tax | GSTR-3B taxable value | GSTR-3B tax | Difference | Reason | Action |
|---|---|---|---|---|---|---|---|
| Apr | |||||||
| … |
Reconcile three ways: books ↔ GSTR-1 ↔ GSTR-3B.
Worked example
Example: Delta Polyplast, a manufacturer in Delhi, finds for FY 2025-26:
| Month | GSTR-1 tax | GSTR-3B tax | Difference | Reason |
|---|---|---|---|---|
| June | ₹4,20,000 | ₹3,80,000 | ₹40,000 | One invoice of ₹2,22,222 (18%) missed in 3B |
| September | ₹3,90,000 | ₹4,10,000 | ₹(20,000) | Credit note reported in GSTR-1 of October, but reduced in September 3B |
| March | ₹5,10,000 | ₹4,50,000 | ₹60,000 | Two invoices dated 31 March, tax paid in April 3B |
Action: - June: pay ₹40,000 with interest through DRC-03 (or in a later 3B), interest at 18% from 21 July to payment date. - September/October: timing difference – no net liability; document in reconciliation. - March: tax paid in April – interest for one month is due on ₹60,000 (about ₹900); disclose in GSTR-9.
Annual return impact
GSTR-9 compares outward supplies declared in GSTR-1 and GSTR-3B. Differences not paid by the annual return must be paid through DRC-03, and the reconciliation in GSTR-9C (for turnover above ₹5 crore) explains differences with books. See GSTR-9 and 9C guide.
Best practices
- Finalise sales in books before the 11th; upload GSTR-1 from the same data.
- Use GSTR-1A to fix errors before 3B.
- Do not file 3B with estimates.
- Run a monthly three-way reconciliation and keep it on file.
- Respond to DRC-01B within 7 days.
Common mistakes
- Paying tax in 3B on an estimate and never correcting.
- Reporting credit notes in different months in the two returns.
- Ignoring small differences that accumulate over the year.
- Not paying interest on delayed tax.
Key takeaway
GSTR-1 and GSTR-3B must tell the same story. Reconcile monthly, use GSTR-1A, and respond to DRC-01B immediately to avoid blocked returns and notices. Our GST return service includes monthly reconciliation reports.
Official references
Provisions discussed (summaries in our Law Library):
- CGST Act, 2017 – Section 39: Returns (GSTR-3B)
Official sources to verify the current text, notifications and circulars:
Frequently asked questions
Why do GSTR-1 and GSTR-3B differ?
Common reasons are invoices missed in one return, amendments, credit notes reported differently, advances, rate or place-of-supply errors, and supplies reported in a different month.
What is DRC-01B?
A system intimation under Rule 88C when the tax liability in GSTR-1 exceeds that paid in GSTR-3B beyond a prescribed limit. You must pay the difference through DRC-03 or explain it in Part B; otherwise the next GSTR-1 filing may be blocked.
What is GSTR-1A?
An optional return to amend or add records in GSTR-1 of the same tax period after filing GSTR-1 but before filing GSTR-3B, so that the auto-populated GSTR-3B is correct.
Can I change auto-populated values in GSTR-3B?
The portal has moved towards locking the outward liability in GSTR-3B to the values from GSTR-1/1A/IFF. Corrections should be made through GSTR-1A or in later GSTR-1 amendments rather than by editing GSTR-3B.
Can I pay extra tax in GSTR-3B to cover future mismatches?
Paying excess tax in GSTR-3B creates an excess that must later be adjusted or refunded; it is better to report correctly and reconcile.
Is interest payable on tax paid in a later month's GSTR-3B?
Yes. Interest at 18% applies on the tax (net of ITC, cash portion) from the original due date to the date of payment.
Can GSTR-1 be amended after GSTR-3B is filed?
Yes, in a later month's GSTR-1, up to 30 November following the financial year; GSTR-1A works only before filing GSTR-3B of the same period.
This article is general information on the law as on 10 November 2026, written for educational purposes. It is not professional advice for your case. Section numbers under the Income-tax Act, 2025 should be confirmed with the official section mapping on the Income Tax Department website before use in filings.
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