How to Make a GST Invoice: A Step-by-Step Guide

A GST invoice is the most important document in your business — it is the legal proof of a sale and the basis for your customer's input tax credit. Getting it right keeps you compliant and your customers happy. Here is exactly how to make one.

What is a GST invoice?

A GST (tax) invoice is a document a registered seller issues to a buyer for goods or services supplied. It records the items, the GST charged, and the details of both parties. Under GST law, it must be issued within prescribed time limits and must contain a set of mandatory fields.

Mandatory fields on a GST invoice

Every GST-compliant invoice should include:

• Your business name, address and GSTIN
• A unique, sequential invoice number and the invoice date
• Customer name, address and GSTIN (for B2B)
• Place of supply and state code
• Description of goods/services with the HSN or SAC code
• Quantity, unit, rate and taxable value
• GST rate and amount, split into CGST + SGST or IGST
• Total invoice value (in figures and, where required, words)
• Signature or digital signature of the supplier

How GST is split: CGST, SGST and IGST

The way GST is applied depends on the place of supply:

• Within the same state (intra-state): the tax is split equally into CGST and SGST. For example, 18% GST becomes 9% CGST + 9% SGST.
• Between different states (inter-state): a single IGST at the full rate (e.g. 18%) applies.

Getting the place of supply right is essential — it decides which tax you charge.

Step-by-step: creating the invoice

• 1. Add your business and customer details — including both GSTINs for B2B sales.
• 2. List the items with HSN/SAC codes, quantity and rate.
• 3. Apply the correct GST rate and let it split into CGST/SGST or IGST based on the state.
• 4. Check the totals — taxable value, tax and grand total.
• 5. Number it sequentially and issue it to your customer.

Do it automatically with SmartVyapar

Doing all this by hand in Excel is slow and error-prone. With SmartVyapar, you pick a party, add items, and the GST, HSN, place-of-supply split and totals are calculated for you — then you print or share a professional PDF in seconds. Every invoice also flows straight into your GSTR-1 and reports, so there is no double entry.