What a valid Indian GST invoice must include

Per Rule 46 of the CGST Rules, every tax invoice for a registered taxpayer must show:

• Supplier's name, address and GSTIN
• Invoice number (consecutive, unique per FY) and date
• Recipient's name, address and GSTIN (if registered)
• HSN code (for goods) or SAC code (for services)
• Description, quantity, rate, taxable value of each item
• Tax rate and amount split into CGST + SGST (intra-state) or IGST (inter-state)
• Total invoice value in figures and words
• Signature or digital signature of supplier

CGST + SGST vs IGST

If supplier and buyer are in the same state, GST splits into CGST (Centre) and SGST (State), each at half the rate. So 18% becomes 9% CGST + 9% SGST. If they're in different states, charge a single IGST at the full rate. The tax total is identical — only routing changes. The tool toggles between these based on the “Inter-state” checkbox.

When you don't need a GST invoice

• If your annual turnover is below ₹20 lakh (₹10 L for some special-category states), you may not need to register.
• Composition-scheme taxpayers issue a “bill of supply”, not a tax invoice.
• Exempt or zero-rated supplies issue a bill of supply.