Filing GST returns is mandatory for all registered taxpayers. This comprehensive guide covers the two main monthly returns - GSTR-1 and GSTR-3B - with step-by-step filing instructions.
Understanding GST Returns
GST returns are documents containing details of income/sales and expenses/purchases that taxpayers must file with tax authorities. There are different types based on business type and tax regime.
| Return Type | Purpose | Due Date | Frequency |
|---|---|---|---|
| GSTR-1 | Outward supplies (Sales) | 11th of next month | Monthly |
| GSTR-3B | Summary return + Tax payment | 20th of next month | Monthly |
| GSTR-2A/2B | Auto-populated purchase data | View only | - |
| GSTR-4 | Composition scheme | 18th of month after quarter | Quarterly |
💡 Key Concept
GSTR-1 reports your sales → GSTR-3B is where you pay tax. They must match to avoid notices.
Filing GSTR-1 (Outward Supplies)
What to Report in GSTR-1
- B2B invoices (with GSTIN)
- B2C large invoices (>₹2.5 lakh)
- B2C small invoices (consolidated)
- Credit/debit notes
- Exports
1Login to GST Portal
Visit www.gst.gov.in → Login with username/password → Services → Returns → Returns Dashboard
2Select Financial Year & Return Period
Choose FY and month for which you're filing GSTR-1
3Enter Invoice Details
Table 4 (B2B): Add invoices with customer GSTIN, invoice number, date, value, taxable value, GST amount
Table 5 (B2C Large): Invoices >₹2.5 lakh without GSTIN
Table 7 (B2C Small): Consolidated sales by state and rate
4Review & Submit
Check summary, preview, and submit. File with DSC or EVC (OTP).
⚠️ Common GSTR-1 Mistakes
- Wrong customer GSTIN - buyer won't get ITC
- Incorrect invoice date - system rejects
- Missing HSN code - mandatory for turnover >₹5 Cr
- Wrong place of supply - affects IGST/CGST+SGST
Filing GSTR-3B (Summary Return)
What to Report in GSTR-3B
- Output tax liability (from sales)
- Input tax credit (from purchases)
- Tax payable (Output - ITC)
- Interest & late fee (if applicable)
1Access GSTR-3B
GST Portal → Returns Dashboard → GSTR-3B → Prepare Online
2Fill Table 3.1 (Output Tax)
Enter tax on outward supplies:
- 3.1(a) - Taxable outward supplies
- 3.1(b) - Outward supplies to composition dealers
- 3.1(c) - Zero-rated supplies (exports)
- 3.1(d) - Reverse charge purchases
3Fill Table 4 (Input Tax Credit)
Based on GSTR-2B (auto-populated purchase data):
- 4(A) - ITC available
- 4(B) - ITC reversed
- 4(D) - Net ITC available
4Calculate Tax Payable (Table 6.1)
System auto-calculates: Tax payable = Output tax (Table 3.1) - ITC (Table 4)
Pay using: ITC ledger → Cash (if ITC insufficient)
5Submit & File
Verify all entries → Submit → File with DSC/EVC
Calculate Tax Liability Before Filing
Use our GSTR-3B Helper to calculate output tax, ITC, and net payable amount.
Calculate Now →ITC Claiming from GSTR-2B
GSTR-2B is an auto-generated statement showing:
- All purchases where suppliers have uploaded invoices
- ITC available for claim
- Generated on 14th of next month
How to Reconcile GSTR-2B
- Download GSTR-2B from portal (14th onwards)
- Match with your purchase records
- Identify missing invoices (follow up with suppliers)
- Claim only matched ITC in GSTR-3B Table 4
- Reverse unmatched ITC if already claimed
💡 Pro Tip: Reconciliation Matters
The government matches GSTR-1 (supplier's sales) with GSTR-3B (your ITC claims). Mismatches trigger notices. Always reconcile GSTR-2B before filing GSTR-3B.
Payment of GST
How to Pay GST Online
- Login to GST Portal → Services → Payments → Create Challan
- Select tax type (IGST/CGST/SGST) and amount
- Generate challan (CPIN number)
- Pay via: Net banking / Debit card / NEFT/RTGS / OTC
- Save payment confirmation
Using ITC for Payment
ITC can be used in this sequence:
- IGST credit → IGST liability (then CGST, then SGST)
- CGST credit → CGST liability (then IGST)
- SGST credit → SGST liability (then IGST)
Late Filing Penalties
| Return | Penalty | Maximum |
|---|---|---|
| GSTR-1 | ₹50/day (₹20/day if turnover <₹1.5 Cr) | ₹10,000 |
| GSTR-3B | ₹50/day (₹20/day if turnover <₹1.5 Cr) | ₹5,000 |
| Interest | 18% p.a. on unpaid tax | No cap |
⚠️ File Nil Returns Too!
Even with zero sales/purchases, you must file nil returns. Use our Penalty Calculator to estimate late filing costs.
Common Filing Issues & Solutions
Issue: GSTR-1 and GSTR-3B Mismatch
Solution: Ensure figures in GSTR-1 Tables 4, 5, 7 match GSTR-3B Table 3.1. File GSTR-1 first, then GSTR-3B.
Issue: Cannot Claim Full ITC
Solution: Check GSTR-2B. Only claim ITC where supplier has filed GSTR-1. Wait for supplier to file or claim in next month.
Issue: Wrong Tax Head Payment
Solution: File refund application or adjust in next month's return with proper entries.
Return Filing Checklist
Before filing, ensure:
- ✓ All invoices entered correctly
- ✓ GSTR-2B reconciled
- ✓ HSN codes provided (if applicable)
- ✓ GSTR-1 filed before GSTR-3B
- ✓ Sufficient balance in cash/ITC ledger
- ✓ Payment made if tax due
- ✓ Filed before deadline (avoid penalties)