How to Create a Professional Invoice — GST Invoice Format India

GST Invoice Complete Guide: Mandatory Fields and Best Practices for Indian Businesses

A GST invoice is a legal document. Errors cause ITC rejection for customers, GST notices, and penalties. This guide covers every mandatory field, invoice types, numbering rules, and how to use Lazyblink Invoice Generator.

Mandatory Fields on Every GST Tax Invoice

As per CGST Rules 2017, every tax invoice from a registered taxpayer must include all of the following:

Supplier details: Full legal name as per GST registration, complete registered address, and 15-digit GSTIN.

Invoice identification: Consecutive invoice number (alphanumeric, maximum 16 characters, unique per financial year) and invoice date.

Recipient details for B2B: Name, address, and GSTIN of the registered recipient. For unregistered recipients above Rs 50,000: name, address, and state.

Per line item: Description of goods or services, HSN code for goods or SAC code for services, quantity and unit of measure for goods, unit price, and any discount.

Tax calculation: Taxable value after discounts, applicable GST rate, CGST and SGST amounts for intra-state supply OR IGST amount for inter-state supply, and total invoice value in words and figures.

Additional required fields: Place of supply (determines CGST+SGST vs IGST), whether reverse charge applies, and supplier signature or digital signature.

HSN and SAC Code Requirements

Annual Turnover

Digits Required

|---|---|

Up to Rs 5 crore	4-digit HSN or SAC
Rs 5 crore and above	6-digit HSN or SAC
Export invoices	8-digit HSN mandatory

Common SAC codes: 998313 for software development, 998314 for IT consulting, 9983 for other professional services, 9972 for real estate.

Invoice Types Under GST

Tax Invoice: Issued by registered taxpayer for taxable supplies. Buyer can claim ITC. This is the standard invoice for most businesses.

Bill of Supply: Issued by composition dealers or for exempt supplies. No GST charged, no ITC available to buyer.

Receipt Voucher: Issued when advance payment is received before supply. Required to be issued at time of receiving advance.

Refund Voucher: Issued when advance is returned without supply happening. Cancels the receipt voucher.

Debit Note: Issued when original invoice amount was too low. Additional GST is charged.

Credit Note: Issued when original invoice amount was too high or goods are returned. Reduces tax liability.

Delivery Challan: For goods movement without a sale (job work, consignment). Not a tax invoice.

Invoice Numbering System

GST requires consecutive serial numbering within each financial year. Maximum 16 characters. Can include letters, numbers, hyphens, and slashes. No spaces. Reset to 0001 on April 1 each year.

Recommended format: INV-2425-0001 for first invoice of FY 2024-25. Or ABC/24-25/001 where ABC is your business abbreviation.

Common Payment Terms

Net 30: Payment due within 30 days — standard for most B2B. Net 15: Payment due within 15 days. Due on Receipt: Immediate payment expected. 2/10 Net 30: 2% discount if paid within 10 days, full amount due in 30 days.

Late payment interest is enforceable: state the rate on the invoice. "Interest at 18% per annum on invoices unpaid after 30 days" is legally enforceable through civil court if stated in the invoice terms.

Export Invoice Requirements

Mark as: "Supply Meant for Export Under Bond or LUT Without Payment of IGST" for most service exports. Include recipient country name and address, currency of payment, and shipping bill number once available. The LUT (Letter of Undertaking) number must be mentioned for zero-rated exports.

Using Lazyblink Invoice Generator

Enter your business name, address, and GSTIN — save as template for repeat use. Enter customer details including GSTIN for B2B transactions. Add line items with HSN or SAC codes, quantities, and rates. Select GST rate — the tool automatically calculates CGST and SGST for intra-state or IGST for inter-state based on your place of supply. Add payment terms and bank details. Preview the invoice and download as PDF. All data is processed in your browser — nothing is stored on any server. Free with no watermark.