Free GST Invoice Generator India — Complete Step-by-Step Guide (2025)

What is a GST Invoice?

A GST invoice is a legal document issued by a GST-registered supplier to a buyer. It records the details of goods or services sold, the applicable GST rate, and the total amount payable. Under Indian GST law, registered businesses must issue a proper tax invoice for every B2B transaction.

What Must a GST Invoice Contain?

As per GST rules, every tax invoice must include these mandatory fields:

• Supplier's name and address
• Supplier's GSTIN (15-digit GST Identification Number)
• Invoice number (sequential, no gaps allowed)
• Invoice date
• Buyer's name and address
• Buyer's GSTIN (for B2B transactions)
• Description of goods/services
• HSN/SAC code (for businesses above ₹5 crore turnover)
• Quantity and unit
• Taxable value
• GST rate and amount (CGST + SGST or IGST)
• Total invoice value
• Place of supply

How to Calculate GST on an Invoice

GST in India is calculated as a percentage of the taxable value. Common GST rates are 0%, 5%, 12%, 18% and 28%.

Formula:

• Taxable Value = Sale price before GST
• GST Amount = Taxable Value × GST Rate ÷ 100
• Total Invoice Value = Taxable Value + GST Amount

Example: You sell a mobile phone for ₹10,000. GST rate is 18%.

• Taxable Value = ₹10,000
• GST (18%) = ₹1,800
• Total = ₹11,800

For intra-state sales: CGST = 9% + SGST = 9% (totalling 18%)
For inter-state sales: IGST = 18%

How to Generate a Free GST Invoice

You don't need expensive accounting software to create GST invoices. BillingBro is a free online GST invoice generator that creates compliant invoices in seconds.

Step 1: Register Your Shop

Go to billingbro.com/register.html and create a free account. Enter your shop name, address and GSTIN.

Step 2: Fill Invoice Details

Enter the customer's name and mobile number. Add items with descriptions, quantities and rates. Enter the GST percentage — BillingBro calculates the GST amount and total automatically.

Step 3: Save and Share

Click Save to store the invoice in your account. Click WhatsApp to send the formatted invoice directly to your customer. Click Print to download a PDF.

Common GST Invoice Mistakes to Avoid

• Wrong GSTIN — always double-check your 15-digit number
• Non-sequential invoice numbers — numbers must be sequential within a financial year
• Wrong GST rate — verify the correct slab for your goods/services
• Missing place of supply — essential for determining CGST/SGST vs IGST
• Incorrect HSN code — use the correct code for your product category

Conclusion

Creating GST invoices doesn't need to be complicated or expensive. With a free tool like BillingBro, you can generate fully compliant GST invoices, send them via WhatsApp and maintain a complete invoice history — all at zero cost.