How to Raise a GST-Compliant Tax Invoice: Mandatory Fields and E-Invoicing

Mandatory fields on a tax invoice

Rule 46 lists the particulars a tax invoice must carry. Missing fields can lead buyers to lose input tax credit and suppliers to face penalties, so build them into your invoice template once and keep it locked.

• Supplier's name, address and GSTIN
• Consecutive serial number (unique for the financial year)
• Date of issue
• Recipient's name, address and GSTIN (B2B)
• Place of supply with state name (inter-state)
• HSN code for goods or SAC for services
• Description, quantity and unit
• Total value and taxable value after discounts
• Tax rate and amount of CGST, SGST/UTGST, IGST and cess
• Whether tax is payable on reverse charge
• Signature or digital signature

HSN codes and tax rates

Businesses with aggregate turnover up to ₹5 crore must show at least four-digit HSN codes on B2B invoices; those above ₹5 crore must show six digits. The GST rate structure was rationalised with effect from 22 September 2025 into a main 5% and 18% structure with a 40% rate for specified goods, alongside special rates such as those for precious metals. Check the current rate notification for each product, because many items moved slabs in that reform.

When must the invoice be issued?

For goods, issue the invoice before or at the time of removal or delivery. For services, issue it within 30 days of supply. Advances received for services require a receipt voucher, and the tax liability arises on receipt. Exempt supplies and composition dealers use a bill of supply instead of a tax invoice. Exports under LUT carry the endorsement that supply is meant for export without payment of IGST.

E-invoicing and the IRN

Businesses whose aggregate turnover exceeded ₹5 crore in any financial year since 2017-18 must report B2B invoices, exports and credit or debit notes to the Invoice Registration Portal and print the IRN and QR code on the invoice. An invoice without a valid IRN is not a valid tax invoice. From 1 April 2025, taxpayers with turnover of ₹10 crore or more cannot report an invoice to the IRP more than 30 days after its date, so build daily or weekly IRN generation into billing.

Credit notes and corrections

Do not edit or cancel an invoice once it is reported in GSTR-1; issue a credit or debit note instead. E-invoices can be cancelled on the IRP within 24 hours if not yet used in returns or e-way bills. Credit notes for a financial year must be declared by 30 November of the following year, and the buyer must reverse the corresponding credit.

Common mistakes

Common errors include using the wrong place of supply for inter-state services, charging CGST and SGST instead of IGST, reusing invoice numbers across years without a prefix, missing HSN codes and issuing e-invoices late. Each one can cost the buyer its credit and damage your relationship.

Step by step

1. 1Set up template

   Include all Rule 46 fields and your GSTIN.

2. 2Determine place of supply

   Decide intra-state or inter-state and the tax type.

3. 3Apply HSN and rate

   Use correct HSN/SAC digits and the current GST rate.

4. 4Number sequentially

   Use a unique serial number per financial year.

5. 5Generate IRN if required

   Report to the IRP if your turnover exceeds ₹5 crore.

6. 6Issue on time

   Before removal of goods or within 30 days for services.

7. 7Report in GSTR-1

   Include the invoice in the period's GSTR-1.