Last updated: 6 April 2026. GSTR-1 and GSTR-3B are the two returns every regular GST taxpayer files every month — but they serve completely different purposes. GSTR-1 is a report of your sales; GSTR-3B is where you pay your tax. When these two returns show inconsistent figures, a significant mismatch may trigger a DRC-01B intimation under Rule 88C which can lead to blocking of your next GSTR-1 filing if not responded to within 7 days — with no manual intervention from a tax officer required.
Applicability Note: This guide is based on GST provisions applicable as of 6 April 2026, including Rules 88C and 88D of the CGST Rules and the CGST Act as amended. Always verify the current position on gst.gov.in or with a GST professional before taking action.
Who Should Care?
This guide applies to:
- All regular GST-registered taxpayers filing monthly GSTR-1 and GSTR-3B
- QRMP scheme taxpayers who file quarterly GSTR-1 and GSTR-3B
- Accounts teams responsible for ensuring return figures match before filing
- Taxpayers who have received a DRC-01B or DRC-01C notice
1. What Is GSTR-1?
GSTR-1 is a statement of outward supplies — a complete record of all sales made during a given tax period. It is a reporting form, not a payment form. No tax is paid when you file GSTR-1; you are declaring your sales to the GST system.
Every B2B invoice, B2C transaction, credit note, debit note, and export must be reported in GSTR-1. Once filed, this data automatically flows into your buyer's GSTR-2B — the auto-generated ITC statement. If you file GSTR-1 late, your buyer's GSTR-2B does not reflect your invoices, and they cannot claim ITC on their purchases from you for that period.
| Taxpayer Type | GSTR-1 Due Date |
|---|---|
| Monthly filers (turnover > ₹5 crore, or opted out of QRMP) | 11th of the following month |
| QRMP filers — full quarterly GSTR-1 | 13th of month following the quarter |
| QRMP filers — IFF (Invoice Furnishing Facility) for B2B invoices | 13th of the following month (months 1 and 2 of quarter) |
2. What Is GSTR-3B?
GSTR-3B is a self-declared summary return through which a taxpayer declares their total tax liability, claims ITC, and pays the net tax due to the government. Unlike GSTR-1, GSTR-3B directly results in tax payment — filing it without paying the full tax liability results in interest at 18% per annum under Section 50 of the CGST Act from the due date.
GSTR-3B does not require invoice-level details. It is a summary declaration covering: outward taxable supplies, inward supplies under reverse charge, eligible ITC, ITC reversals, and net tax payable under IGST, CGST, and SGST/UTGST.
| Taxpayer Type | GSTR-3B Due Date |
|---|---|
| Monthly filers | 20th of the following month |
| QRMP filers — Category I states | 22nd of month following the quarter |
| QRMP filers — Category II states | 24th of month following the quarter |
3. GSTR-1 vs GSTR-3B: Side-by-Side Comparison
| Feature | GSTR-1 | GSTR-3B |
|---|---|---|
| Purpose | Reports outward supplies (sales) | Summary of tax liability, ITC, and tax payment |
| Nature | Statement / Reporting form | Self-declared summary return |
| Tax payment involved? | No | Yes |
| Level of detail | Invoice-level | Summary-level |
| Impact on buyer? | Yes — feeds buyer's GSTR-2B for ITC | No direct impact on buyer |
| Amendment mechanism | Next month's GSTR-1 (Table 9/10) | Correction in the subsequent period |
| Late filing fee | ₹50/day (as reduced from the statutory ₹200/day by notification), subject to the same turnover-based caps as GSTR-3B | ₹50/day (nil: ₹20/day), subject to turnover-based caps (per CGST Notifications 19-21/2021 dated 1 June 2021): • Up to ₹1.5 crore: max ₹2,000 (₹1,000 CGST + ₹1,000 SGST) • ₹1.5–₹5 crore: max ₹5,000 (₹2,500 + ₹2,500) • Above ₹5 crore: max ₹10,000 (₹5,000 + ₹5,000) • Nil returns: max ₹500 (₹250 + ₹250) |
4. Two Types of Automated Mismatch Notices — DRC-01B and DRC-01C
The GST system runs automated checks comparing your returns. Two distinct notices can arise, and they are commonly confused:
| Notice | Rule | What Triggers It | Threshold |
|---|---|---|---|
| DRC-01B | Rule 88C | Tax declared in GSTR-1 exceeds tax declared in GSTR-3B (under-payment indicator) | Prescribed under Rule 88C and configured in the GST portal. Verify the current trigger parameters on gst.gov.in, as these have been updated since the rule's initial notification. |
| DRC-01C | Rule 88D | ITC claimed in GSTR-3B exceeds ITC available in GSTR-2B (excess ITC claim) | Difference > ₹1 lakh or 20% of GSTR-2B ITC, whichever is lower |
Both notices must be responded to within 7 days. If you do not respond, non-response can lead to blocking of your GSTR-1 filing for the next period under Rule 59(6) of the CGST Rules — no officer action required.
DRC-01B: GSTR-1 vs GSTR-3B Outward Supply Mismatch (Rule 88C)
If your GSTR-1 shows a higher tax liability than your GSTR-3B for the same period and the mismatch exceeds the prescribed threshold under Rule 88C, the GST portal issues a DRC-01B intimation. The threshold is prescribed under Rule 88C and configured in the GST portal — verify the current trigger parameters on gst.gov.in, as these have been updated since the rule's initial notification. This suggests you may have under-paid tax in GSTR-3B compared to what you declared in GSTR-1.
Common causes: B2B invoices reported in GSTR-1 but accidentally omitted from GSTR-3B; credit notes in GSTR-1 not reflected in GSTR-3B; amendments in GSTR-1 for a prior period not carried into GSTR-3B.
To respond: either pay the differential tax via Form DRC-03 (with applicable interest under Section 50) or submit a detailed explanation with supporting reconciliation on the GST portal.
DRC-01C: GSTR-2B vs GSTR-3B ITC Mismatch (Rule 88D)
If the ITC you claimed in GSTR-3B exceeds the ITC available in your GSTR-2B by more than ₹1 lakh or 20%, the system issues a DRC-01C intimation. This is the ITC excess claim check — it has nothing to do with your outward supplies.
To respond: pay the excess ITC amount in cash via DRC-03, or explain the discrepancy (e.g., invoices confirmed with supplier but not yet reflected in GSTR-2B due to supplier's delayed filing) with supporting documents.
5. How to Avoid Both Types of Notices
- File GSTR-1 before GSTR-3B: Always file GSTR-1 first so your outward supply data is already declared before you make the tax payment in GSTR-3B
- Match GSTR-1 totals with GSTR-3B Table 3.1: After filing GSTR-1, verify that the total taxable value and tax liability match the figures you enter in GSTR-3B — even a small difference can cross the Rule 88C threshold
- Reconcile GSTR-2B before claiming ITC: Download GSTR-2B and reconcile it with your purchase register before filing GSTR-3B — only claim ITC that is reflected in GSTR-2B
- Monitor the GST portal weekly: DRC-01B and DRC-01C notices have a 7-day response window. Set up email and SMS alerts on the portal for your GSTIN
- Correct GSTR-1 errors in the next month: Errors in GSTR-1 cannot be edited after filing — use Table 9 (B2B amendments) or Table 10 (B2C large amendments) in the next month's GSTR-1
Key Takeaways
- GSTR-1 is for reporting sales; GSTR-3B is for paying tax — both must be filed on time and must be consistent with each other
- GSTR-1 vs GSTR-3B mismatch triggers a DRC-01B notice under Rule 88C — not DRC-01C
- GSTR-2B vs GSTR-3B ITC mismatch triggers a DRC-01C notice under Rule 88D
- DRC-01B threshold is prescribed under Rule 88C; DRC-01C threshold under Rule 88D — both are configured in the GST portal. Verify current trigger parameters on gst.gov.in
- Both notices require a response within 7 days — non-response blocks GSTR-1 filing for the next period automatically
- Late GSTR-1 harms your buyers by removing their invoices from GSTR-2B and blocking their ITC claims
Frequently Asked Questions
What is the difference between GSTR-1 and GSTR-3B?
GSTR-1 is a statement of all outward supplies (sales) — it is a reporting form with no tax payment. GSTR-3B is a summary return through which you declare your tax liability, claim ITC, and pay the net tax due. GSTR-1 feeds your buyers' GSTR-2B for ITC; GSTR-3B discharges your own tax liability. Both must be filed separately and must be consistent with each other.
What happens if GSTR-1 shows more tax than GSTR-3B?
The GST system will issue a DRC-01B intimation under Rule 88C if the mismatch exceeds the prescribed threshold under Rule 88C (verify current parameters on gst.gov.in, as these have been updated since the rule's initial notification). This suggests a possible under-payment of tax. You must respond within 7 days — either by paying the differential tax with interest via DRC-03 or by filing an explanation on the portal. Non-response can lead to blocking of your next GSTR-1 filing under Rule 59(6).
Can I file GSTR-3B without filing GSTR-1?
Yes, technically — but this creates a mismatch and your buyers will not see your invoices in their GSTR-2B for that period, which blocks their ITC claims. It is strongly advisable to file GSTR-1 before GSTR-3B every month. The GSTR-1 and GSTR-3B must also be consistent to avoid automated DRC-01B notices.
What is a DRC-01B notice and how is it different from DRC-01C?
DRC-01B is issued under Rule 88C when your declared tax liability in GSTR-1 significantly exceeds what you paid in GSTR-3B (outward supply mismatch). DRC-01C is issued under Rule 88D when the ITC you claimed in GSTR-3B exceeds your GSTR-2B ITC by the threshold amount (ITC mismatch). Both require response within 7 days — but they address different compliance issues.
Is a nil GSTR-1 mandatory even when there are no sales?
Yes. If there are no outward supplies in a period, a nil GSTR-1 must still be filed. Failure to file attracts a late fee of ₹20 per day subject to a maximum of ₹500 (₹250 CGST + ₹250 SGST). Filing the nil return also signals to the GST system and your buyers that you had no transactions to report — this prevents system-generated discrepancy alerts.
Disclaimer: This article is for informational purposes only and does not constitute professional tax advice. GST rules are subject to frequent changes through notifications and circulars. Please consult a qualified tax professional or verify the current provisions on the official GST portal (gst.gov.in) before making any compliance decisions.
Have a specific question about GSTR-1, GSTR-3B, or a DRC-01B/DRC-01C notice? Our GST experts can help → gstconsultancy.com