How to Generate a Valid GST Invoice Online
A valid GST invoice must follow Rule 46 of the CGST Rules 2017. Every invoice you generate on GSTInvoiceFree.in automatically includes all mandatory fields — your GSTIN, buyer GSTIN, HSN or SAC code, Place of Supply, and a full tax breakup showing CGST, SGST, or IGST.
HSN vs SAC code: If you're supplying goods, use an HSN (Harmonised System of Nomenclature) code. If you're a service provider — freelancer, consultant, agency — use a SAC (Service Accounting Code). The tool accepts both. Not sure which applies? Your CA or the CBIC HSN search tool can confirm the right code for your business type.
CGST+SGST vs IGST: The tool detects this automatically. If your state and your client's state match — same state supply — CGST and SGST apply at equal rates. If they're different states — interstate supply — IGST applies at the full rate. The total tax amount is identical either way. If you want to understand this in depth, read our guide on the difference between CGST, SGST and IGST.
Invoice number rules: Your invoice number must be sequential, unique within a financial year, and no longer than 16 characters. It resets every April 1. For a full breakdown of the invoice number rules and format requirements, see our GST invoice format guide. If you're looking for a ready-to-use template in Excel, Word, or PDF, check our free GST invoice template guide.
Frequently Asked Questions
Is this free GST invoice generator really free?
Yes — 100% free. No signup, no credit card, no hidden charges. Generate unlimited GST invoices at zero cost, forever.
Is my business data safe? Does it go to any server?
Your data never leaves your browser. All processing happens entirely client-side using JavaScript. We do not store, collect, or transmit any invoice information you enter. The PDF is generated and downloaded directly on your device.
Can I generate a GST invoice without a GSTIN?
If your turnover is below ₹20 lakh (₹10 lakh for special category states), GST registration is not mandatory and you can issue a regular invoice without GSTIN. If you are GST registered, your GSTIN is mandatory on every tax invoice under Rule 46 of the CGST Rules 2017.
How does CGST, SGST and IGST get decided automatically?
The tool compares your state (Place of Supply of the seller) with your client's state. Same state = CGST + SGST at equal split. Different states = IGST at the full rate. Total tax amount is identical either way — only the tax head changes. Read our full guide on CGST vs SGST vs IGST for detailed examples.
What invoice types does this GST invoice generator support?
The tool supports Tax Invoice, Proforma Invoice, Bill of Supply, Export Invoice, and Custom invoice types. Each follows the correct format under Indian GST law. For handwritten invoices, see our guide on whether handwritten GST invoices are legal.