GSTR-1 is a monthly or quarterly return declaring all your outward supplies (sales). It is the source from which your buyers' GSTR-2B is auto-populated — directly affecting their ability to claim Input Tax Credit.
Who Must File GSTR-1?
All GST-registered regular taxpayers. Composition scheme taxpayers are exempt (they file GSTR-4 instead).
Due Dates
| Category | Frequency | Due Date |
|---|---|---|
| Turnover > ₹5 Crore (previous FY) | Monthly | 11th of the following month |
| Turnover ≤ ₹5 Crore (QRMP scheme) | Quarterly | 13th of next month after quarter end |
| QRMP — IFF (optional B2B monthly upload) | Monthly (M1 & M2 only) | 13th of following month |
Key Tables in GSTR-1
| Table | What to Enter |
|---|---|
| 4A / 4B / 4C | B2B invoices (with buyer GSTIN) |
| 5A / 5B | B2C Large invoices (inter-state, above ₹2.5L) |
| 5A-II | B2C Others (consolidated — small & intra-state) |
| 6A / 6B | Export invoices (with/without tax payment) |
| 9B | Credit Notes issued to GST-registered buyers |
| 9C | Debit Notes issued to GST-registered buyers |
| 12 | HSN/SAC-wise summary of all supplies |
Late Filing Penalties
- ₹50/day (₹25 CGST + ₹25 SGST) for taxable returns
- ₹20/day (₹10 CGST + ₹10 SGST) for nil returns
- Maximum ₹10,000 per return period
- Buyers cannot see your invoices in their GSTR-2B — blocking their ITC until you file
Pro Tip
Kallapotti exports GSTR-1-ready JSON from your billing data — just upload directly to the GST portal without any manual data entry.