How to Write a GST Invoice (With Free Template)

A GST tax invoice in India must show your business details and GSTIN, the buyer's details (and GSTIN for B2B), a unique sequential invoice number and date, a description with HSN/SAC codes, quantity and taxable value, the GST rate and amount (CGST + SGST or IGST), place of supply, and an authorised signature. Get these right and your customers can claim input tax credit smoothly. Here's the format, a worked example and a free tool.

This guide is general information, not tax advice. Rules change, so confirm specifics with your chartered accountant (as of Sept 2026).

Mandatory fields on a GST tax invoice

Field	Notes
Supplier name, address, GSTIN	Your registered details
Invoice number	Unique, consecutive, max 16 characters, per financial year
Invoice date	Date of issue
Recipient name, address	Buyer details
Recipient GSTIN	Mandatory for B2B (registered buyers)
Place of supply + state	Determines CGST/SGST vs IGST
Description of goods/services	Clear and specific
HSN (goods) / SAC (services) code	As per applicable rules
Quantity and unit	For goods
Taxable value	After discounts
GST rate and amount	CGST + SGST, or IGST
Total invoice value	In figures (words optional but common)
Reverse charge applicability	Yes/No
Signature	Physical or digital

CGST + SGST or IGST?

Same state (supplier and place of supply in, say, Rajasthan): charge CGST + SGST, each half the rate. 18% becomes 9% + 9%.
Different state (supplier in Rajasthan, buyer in Maharashtra): charge IGST at the full rate. 18% stays 18%.
Exports: zero-rated under LUT or with IGST paid. Consult your CA.

Worked example

A Jaipur agency bills a Jaipur client for a website worth ₹54,999 (SAC 998314, IT design and development services):

Item	Amount
Taxable value	₹54,999.00
CGST @ 9%	₹4,949.91
SGST @ 9%	₹4,949.91
Total	₹64,898.82

If the client were in Pune, it would instead be IGST @ 18% = ₹9,899.82, for the same total.

Numbering best practices

Use a prefix per financial year: RB/25-26/0001
Never skip or reuse numbers; cancel with a credit note instead
Keep separate series for different branches, if needed

Credit and debit notes

Credit note: to reduce the value (returns, discounts after sale, over-billing)
Debit note: to increase the value (under-billing)
Both reference the original invoice number

Create one free in 2 minutes

Use our free GST invoice generator. Add your logo and GSTIN, pick intra- or inter-state, add line items, and download a PDF. It works in your browser; nothing is uploaded.

Automate invoicing

If you raise many invoices, a CRM with invoicing saves hours. RapBooster CRM (₹1,799/month, or ₹1,499/month billed yearly, excl. GST, 5 users included) includes invoices, estimates and proposals linked to your leads and deals. See RapBooster CRM.

Related: sales pipeline stages for Indian SMBs and the glossary entry for GST invoice.

Quick answers

Questions readers ask.

Is it mandatory to mention HSN/SAC codes?

HSN/SAC reporting requirements depend on your annual turnover and the type of supply. Most businesses need to mention them. Check the current CBIC notifications or ask your CA.

What is the difference between a tax invoice and a bill of supply?

A tax invoice is issued for taxable supplies by a registered person. A bill of supply is issued for exempt supplies or by composition-scheme taxpayers, who can't charge GST.

Do I need e-invoicing?

E-invoicing (IRN generation) applies to businesses above the turnover threshold notified by the government. Check the current threshold with your CA, as it has been lowered over time.

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