A practical, table-by-table walkthrough of GSTR-1 for FY 2025-26 — invoice formats, HSN reporting rules, IFF, amendments, and the mistakes that cost your buyers their input tax credit.
GSTR-1 is the single most important return for your buyers — every B2B invoice you file here flows into their GSTR-2B and unlocks their input tax credit. File late or file wrong, and you torch trust along with credit. This guide breaks GSTR-1 down table by table, with the exact rules CAs follow in 2025. Our GST return filing service prepares and files GSTR-1 every month.
GSTR-1 is a monthly or quarterly statement of all outward supplies (sales) made by a GST-registered person. It captures invoice-level detail for B2B sales, aggregate detail for B2C small sales, exports, credit/debit notes, advances and amendments. There is no tax payment in GSTR-1.
| Taxpayer type | Frequency | Due date |
|---|---|---|
| Regular taxpayer — monthly | Monthly | 11th of next month |
| Regular taxpayer — QRMP | Quarterly | 13th of month after quarter |
| QRMP — IFF (optional) | Monthly (M1, M2 of quarter) | 13th of next month |
| Composition dealer | Not applicable | Files CMP-08 instead |
| Non-resident, ISD, TDS, TCS | Not applicable | Separate returns |
Every taxable invoice issued to a GST-registered buyer goes here, invoice by invoice. Required fields: GSTIN of buyer, invoice number, invoice date, invoice value, place of supply, reverse charge flag, taxable value, IGST/CGST/SGST/cess.
Validate buyer GSTINs against the GSTN portal before upload — wrong GSTIN = ITC denied to buyer.
Inter-state B2C invoices above ₹1 lakh must be reported invoice-wise. Below that threshold they go to Table 7 as state-wise aggregate.
For zero-rated supplies, the shipping bill number and date are mandatory if exported on payment of IGST and refund is being claimed.
All B2C invoices not covered above — reported as state-wise, rate-wise aggregate. No invoice numbers needed.
Aggregate values of nil-rated, exempt and non-GST outward supplies. Important for HSN consistency and turnover reconciliation.
Amendments can be filed up to 30th November of the following FY (extended from earlier September deadline).
Advances received against future supply of services (B2B) attract GST at the time of receipt. Report here and adjust when invoice is later raised.
| Turnover | HSN digits | B2B / B2C |
|---|---|---|
| Up to ₹5 Cr | 4-digit | Mandatory for B2B, optional for B2C |
| Above ₹5 Cr | 6-digit | Mandatory for both |
Aggregate count of invoices, credit notes, debit notes, delivery challans, receipt vouchers, etc. issued during the period — including cancelled ones.
For QRMP taxpayers, the IFF lets you upload B2B invoices for the first two months of the quarter (deadline 13th of next month) so your buyers can claim ITC without waiting for the quarter-end GSTR-1. IFF is optional, capped at ₹50 lakh of invoice value per month, and only covers B2B + CDN-R + amendments.
₹50/day (₹25 CGST + ₹25 SGST) for late filing, capped based on turnover slabs. ₹20/day for nil returns. Rule 59(6) blocks the next GSTR-1 if previous 3B is unfiled.
11th of the next month for monthly filers; 13th of the month after the quarter for QRMP filers.
Yes — amendments are allowed in Table 9 of subsequent periods, up to 30th November of the following FY.
Yes — 4-digit for turnover up to ₹5 Cr and 6-digit above ₹5 Cr in Table 12. Missing HSN summary blocks filing.
Your GSTR-2B won't reflect those invoices, so you cannot claim ITC. Follow up before the 11th every month.
Yes — via SMS to 14409 (NIL R1 GSTIN MMYYYY) or on the portal in one click.
Senior contributor at Taxpex Consultancy. Reviewed by a practising Chartered Accountant. Published on 23 May 2025 · Updated on 23 May 2025.
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Yes — GSTR-1, GSTR-3B, GSTR-9 and reconciliation with GSTR-2B are all part of our monthly compliance retainer.
via GST Registration & FilingWhen a supplier gives you a GST-inclusive price and you need to break it into base + GST for invoicing or ITC reconciliation.
via Reverse GST CalculatorGST is mandatory only if your turnover exceeds the GST threshold. Otherwise PAN is enough.
via MSME / Udyam RegistrationNo. Processing fees, insurance, GST on fees and stamp duty are excluded and vary per lender. Add them separately to arrive at the true cost of the loan.
via EMI Calculator