GSTR-1 vs GSTR-3B
GSTR-1 and GSTR-3B are the two primary monthly GST returns. They serve different purposes but must be consistent with each other. Here's how they compare, why mismatches happen, and how to reconcile them.
Side-by-Side Comparison
| Aspect | GSTR-1 | GSTR-3B |
|---|---|---|
| Full Name | Goods and Services Tax Return 1 | Goods and Services Tax Return 3B (Summary Return) |
| Purpose | Report all outward supplies (sales) at invoice level | Report consolidated tax liability and make tax payment |
| Detail Level | Invoice-level: each invoice with GSTIN, amount, rate, tax | Summary: total values grouped by category |
| ITC Impact | Enables buyer's ITC — appears in buyer's GSTR-2B | Uses your ITC — you claim credit here against output tax |
| Monthly Due Date | 11th of following month | 20th of following month |
| Quarterly (QRMP) | 13th of following month | 22nd/24th of following month |
| Filing Order | Filed first — supplies must be reported before claiming ITC | Filed after GSTR-1 — uses GSTR-2B data (from your suppliers' GSTR-1) |
| Late Fee | ₹50/day (₹25 nil), max ₹10,000 | ₹50/day (₹25 nil), max ₹10,000 |
| Nil Return | Required if no outward supplies in the period | Required if no outward supplies and no ITC to claim |
| Who Files | Every registered taxpayer (except Composition) | Every registered taxpayer (except Composition) |
Why GSTR-1 Must Be Filed Before GSTR-3B
The GST system is built on invoice matching. Your GSTR-1 provides the data that your buyers use to claim ITC (via their GSTR-2B). Your GSTR-3B uses ITC from your suppliers (via your GSTR-2B) to determine your net tax liability.
The filing chain:
- You file GSTR-1 → your invoices appear in buyers' GSTR-2B
- Your suppliers file GSTR-1 → their invoices appear in your GSTR-2B
- You file GSTR-3B → you claim ITC from your GSTR-2B and pay net tax
- Buyers file GSTR-3B → they claim ITC from their GSTR-2B
If you file GSTR-3B before your suppliers file their GSTR-1, your GSTR-2B may not reflect all eligible ITC, and you'll end up paying more tax than necessary.
Why GSTR-1 and GSTR-3B Must Reconcile
Your GSTR-1 outward supplies (taxable value) should approximately match your GSTR-3B Table 3.1 outward supplies. If they don't, it may indicate:
- Under-reporting of sales in GSTR-3B (tax not paid)
- Over-reporting of sales in GSTR-3B (excess tax paid — may need refund)
- Timing differences in reporting
- Invoices missed in either return
The GSTN portal performs automated matching and may issue scrutiny notices if mismatches exceed certain thresholds. Regular reconciliation helps you identify and correct issues before they become problems.
Common Reasons for Mismatches
Timing differences
Invoices issued in one period may be reported in GSTR-3B in a different period. For example, an invoice dated 28th March may appear in GSTR-1 for March but in GSTR-3B for April.
Impact: Temporary mismatch that usually self-corrects in the next period.
Credit notes not reflected
Credit notes issued in GSTR-1 reduce the taxable value, but if they are not reported in the same period, GSTR-3B may show a higher liability.
Impact: Overstated tax liability in the earlier period, understated in the later period.
Amendments
Amended invoices in GSTR-1 may not have a corresponding amendment in GSTR-3B, leading to differences.
Impact: Discrepancy between reported and actual tax liability.
Reverse charge not accounted
GSTR-3B includes reverse charge liability (Table 3.1, reverse charge column), but GSTR-1 doesn't capture this — it only captures your outward supplies.
Impact: GSTR-3B may show higher liability than GSTR-1 due to reverse charge additions.
Exempt/nil-rated supplies
GSTR-1 reports nil-rated and exempt supplies in Table 8. If these are not correctly reflected in GSTR-3B Table 5.1, a mismatch occurs.
Impact: Usually immaterial (no tax impact), but may trigger scrutiny.
ITC claimed in excess
If you claim more ITC in GSTR-3B than what appears in your GSTR-2B, your net tax liability in GSTR-3B will be lower than expected.
Impact: May result in interest liability if ITC is reversed later.
Reconcile Your Returns
GSTSelf can automatically compare your GSTR-1 and GSTR-3B data, identify mismatches, and highlight potential issues. All processing happens in your browser.