GST Invoice Rules 2026: What Every Indian Business Must Know
By MsgBill Team•18 February 2026
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GST rules for invoices can change. Here's what Indian businesses must know in 2026 to stay compliant and avoid penalties.
Mandatory Fields on a GST Invoice
- Invoice number (consecutive, unique)
- Invoice date
- Supplier name, address, GSTIN
- Customer name, address, GSTIN (if registered)
- Place of supply
- HSN/SAC code
- Taxable value, tax rate, CGST/SGST/IGST, total
- Reverse charge mention (if applicable)
CGST vs SGST vs IGST
Intra-state: Same state → CGST + SGST. Inter-state: Different state → IGST. Your software should auto-calculate based on place of supply. MsgBill does this when you select business and client state.
Common Mistakes That Lead to Penalties
- Wrong tax rate (e.g., 18% on 5% items)
- Missing HSN/SAC codes
- Incorrect place of supply
- Duplicate or non-sequential invoice numbers
Digital Invoices: Are They Valid?
Yes. PDF invoices sent via email or WhatsApp are valid under GST. Rule 46 allows digital invoices. Keep them accessible for audit.