How to Create a GST Invoice in India — Complete Guide 2026

Mandatory fields on a GST invoice

Section 31 of the CGST Act, read with Rule 46, sets out what every tax invoice must carry: invoice number and date, supplier's name/address/GSTIN, buyer's details (and GSTIN, if registered), HSN/SAC code for each item, description, quantity, unit, total value, taxable value, applicable GST rate, the CGST/SGST/IGST amounts charged, place of supply (for inter-state supplies), and the supplier's signature or digital signature.

CGST vs SGST vs IGST — when to use which

The rule is simple once you anchor it on the place of supply, not just the buyer's billing address:

• Same state as the seller → split the GST rate equally into CGST + SGST.
• Different state from the seller → charge the full rate as IGST.
• Export / outside India → zero-rated, under LUT or with IGST paid and claimed back as refund.

HSN/SAC codes

HSN (Harmonized System of Nomenclature) codes classify goods; SAC (Services Accounting Code) classifies services. Businesses with turnover above ₹5 crore must use a 6-digit code, and smaller businesses typically use 4 digits. Getting this right matters for GSTR-1 matching and ITC claims on the buyer's side.

Invoice serial number format

Invoice numbers must be sequential and unique for a financial year, with no gaps you can't explain. A common format is ABC/2627/0001 — a short prefix, the financial year (April–March, written as e.g. “2627” for FY2026-27), and a zero-padded running number that resets each new financial year.

How to create a GST invoice with GSTClear

1. Enter your seller details once — GSTClear remembers them for next time.
2. Add the buyer's name, GSTIN (if any), address, and state.
3. Set the place of supply — GSTClear automatically works out CGST+SGST vs IGST.
4. Add line items with HSN code, quantity, rate, and GST%.
5. Download a compliant, ready-to-send PDF.