GSTR-1 is the monthly or quarterly return that every registered taxpayer under GST must file. It contains details of all outward supplies (sales). This guide walks you through the complete GSTR-1 filing process step by step for FY 2026-27.
What is GSTR-1?
GSTR-1 is a return of outward supplies (sales) that must be filed by every regular GST-registered taxpayer. It captures details of:
- B2B invoices (sales to registered businesses)
- B2C large invoices (sales above ₹2.5 lakh to unregistered)
- B2C small invoices (sales below ₹2.5 lakh to unregistered)
- Export invoices (with/without payment of IGST)
- Credit notes and debit notes
- Amendments to previous returns
GSTR-1 Due Dates FY 2026-27
| Filing Frequency | Due Date | Turnover Limit |
|---|---|---|
| Monthly | 11th of next month | Above ₹5 crore (or QRMP opted out) |
| Quarterly (QRMP) | 13th of month after quarter | Up to ₹5 crore (opted for QRMP) |
Rs. 20/day for QRMP filers.
Maximum late fee: ₹5,000. Interest under Section 50: 18% per annum on unpaid tax.
Step-by-Step GSTR-1 Filing Process
Step 1: Prepare Your Sales Data
Before filing, compile all sales data for the tax period:
- Invoice-wise B2B sales (with buyer GSTIN)
- B2C sales summary
- Export sales
- Credit/debit notes
- Nil-rated and exempt supplies
Tip: Use accounting software (Tally, Busy, Zoho Books) to auto-generate this data. Manual compilation is error-prone.
Step 2: Log In to GST Portal
Visit gst.gov.in and log in with your credentials. Navigate to Services > Returns > Returns Dashboard.
Step 3: Select Tax Period
Choose the financial year and month/quarter for which you are filing. Click Search.
Step 4: Fill GSTR-1 Form
GSTR-1 has multiple sections (tables). Fill each one:
| Table | Description | Mandatory? |
|---|---|---|
| 4A, 4B, 4C | B2B invoices (registered buyers) | If applicable |
| 5 | B2C large invoices (> ₹2.5 lakh) | If applicable |
| 6 | Exports (with/without IGST) | If applicable |
| 7 | B2C small sales (summary) | If applicable |
| 8, 9, 10 | Nil-rated, exempt, non-GST supplies | If applicable |
| 9B | Credit / Debit notes | If applicable |
| 11A | Amendments to B2B invoices | If applicable |
| 12 | HSN-wise summary of outward supplies | Mandatory |
Step 5: Verify & Generate Summary
Click Generate GSTR-1 Summary. Verify the totals match your books. Check for any errors flagged by the portal.
Step 6: File With DSC or EVC
Once verified, file GSTR-1 using:
- DSC (Digital Signature Certificate) — for companies and LLPs
- EVC (Electronic Verification Code) — OTP-based, for proprietorships
Common GSTR-1 Filing Errors
- Wrong GSTIN of buyer: Verify buyer GSTIN before entering. Invalid GSTIN = buyer can't claim ITC.
- Missing invoices: Every B2B invoice MUST be reported. Missing entries create ITC mismatch for your buyer.
- Wrong HSN codes: Incorrect HSN affects GST rate and buyer's ITC. Use the official HSN code list.
- Not reporting credit notes: Credit notes must be reported in Table 9B. They reduce your tax liability.
- Amendment delays: Invoices can only be amended in the next GSTR-1 (not retrospectively after 2 periods).
Auto-Prepare GSTR-1 From Your Sales Data
ReconcileAI auto-generates GSTR-1 from your Tally/Busy data. No manual entry needed.
Try GST Calculator Free →QRMP Scheme (Quarterly Filing)
Businesses with turnover up to ₹5 crore can opt for the Quarterly Return Monthly Payment (QRMP) scheme:
- GSTR-1: Filed quarterly (13th of month after quarter)
- GSTR-3B: Filed quarterly, but tax paid monthly
- IFF (Invoice Furnishing Facility): Optional monthly invoice upload for B2B sales
Opt-in window: 1st to 30th of the preceding quarter. Opt-out by changing filing frequency on the portal.
GSTR-1 vs GSTR-3B: Key Differences
| Feature | GSTR-1 | GSTR-3B |
|---|---|---|
| Purpose | Outward supply details | Summary return + tax payment |
| Data | Invoice-wise | Consolidated totals |
| Due Date | 11th of next month | 20th of next month |
| Payment | No payment | Tax payment included |