Quick answer: A valid GST invoice format in India must include supplier and buyer GSTIN (where applicable), invoice number, date, HSN/SAC, taxable value, tax rates, CGST/SGST or IGST amounts, and place of supply ??? on a sequential, traceable invoice series.
Wrong invoice format is one of the top reasons for buyer disputes, ITC rejection, and audit questions. Whether you run a medical store, hardware shop, or distribution firm, your invoice is your legal and commercial proof of every transaction.
Mandatory fields on a GST tax invoice
- Name, address, and GSTIN of supplier
- Invoice number and date (unique sequential series)
- Name, address, and GSTIN of recipient (if registered)
- HSN code for goods or SAC for services
- Description, quantity, unit, and total value of supply
- Taxable value, discount, and tax amount (CGST, SGST, IGST)
- Place of supply and reverse charge indicator (if applicable)
- Signature or digital authentication
Tax invoice vs bill of supply ??? when to use which
Tax invoice: Standard format when GST is charged on the supply.
Bill of supply: Used by composition dealers or for exempt supplies ??? no tax breakup shown as tax invoice.
Using the wrong document type confuses buyers and complicates returns. Configure both templates in your billing software and train staff on selection rules.
Common GST invoice mistakes that cost money
- Duplicate or skipped invoice numbers
- Wrong place of supply ??? incorrect IGST vs CGST/SGST
- HSN at 4-digit when 6/8-digit required for your turnover slab
- Printing rounded totals that do not match line-wise tax math
- Missing buyer GSTIN on B2B sales above threshold