What is a GST invoice?
A GST invoice is a tax invoice issued by a GST-registered business for the supply of goods or services. It is the legal document that allows your buyer to claim Input Tax Credit (ITC) on the GST paid. Without a properly formatted GST invoice, your buyer cannot reduce their GST liability — so every field matters.
Rule 46 of the CGST Rules, 2017 prescribes the mandatory contents of a tax invoice. The invoice must be issued before or at the time of removal of goods (for goods) or within 30 days of supply (for services). Banks and financial institutions have 45 days.
Mandatory fields in a GST invoice format
1. Name, address, and GSTIN of the supplier (your business).
2. A consecutive serial number — maximum 16 characters, alphanumeric with hyphens or slashes — unique for each financial year.
3. Date of issue.
4. Name, address, and GSTIN (if registered) of the recipient.
5. For unregistered recipients where invoice value exceeds ₹50,000: full recipient name, address, and place of delivery.
6. HSN code for goods or SAC code for services (required based on turnover: 4 digits for turnover under ₹5 crore, 6 digits above).
7. Description of goods or services.
8. Quantity and unit of measurement.
9. Total value of supply.
10. Taxable value after discount.
11. Rate of tax (CGST, SGST/UTGST, IGST, Cess).
12. Amount of tax for each component.
13. Place of supply along with state and state code (critical for determining CGST/SGST vs IGST).
14. Delivery address where different from place of supply.
15. Whether tax is payable on reverse charge basis.
16. Signature or digital signature of the supplier or authorized representative.
CGST vs SGST vs IGST — which one applies?
The location of the supplier and the place of supply determine which tax component applies.
When the supplier and the place of supply are in the same state (intra-state), the transaction attracts CGST (Central GST) and SGST (State GST) in equal halves. For example, an 18% tax becomes 9% CGST + 9% SGST.
When the supplier and place of supply are in different states (inter-state), only IGST (Integrated GST) applies at the full rate. An 18% tax becomes 18% IGST.
Exports are zero-rated — no GST applies, but you can claim a refund of input GST through an LUT (Letter of Undertaking) or pay IGST and claim refund.
InvoiceForge detects the GSTIN state code automatically and splits the tax correctly every time. No manual math, no mistakes.
Common GST rates in India
India uses a four-slab GST structure: 5%, 12%, 18%, and 28%, along with 0% for exempted goods. Some items have special lower rates of 0.25% (rough diamonds) and 3% (gold, silver, platinum). Luxury and sin goods attract 28% + Compensation Cess.
Essentials like unbranded food grains, milk, fresh fruits, and educational services are at 0%. Household items such as sugar, tea, coffee, edible oils attract 5%. Standard processed goods, mobile phones, packaged food sit at 12%. Most goods and services including electronics, restaurants (AC), financial services fall at 18%. Luxury cars, tobacco, aerated drinks attract 28% plus cess.
Your HSN/SAC code determines the exact rate. Use the built-in HSN Code Finder tool if you are not sure.
Invoice number rules under GST
Invoice numbers must be consecutive, unique per financial year, and not exceed 16 characters. Only letters, digits, hyphens, and slashes are allowed. Once you issue an invoice number, you cannot reuse it — even if the invoice is cancelled.
Common formats that comply with the rule:
— INV-2026-0001 through INV-2026-9999 (year + sequence).
— SHARMA/2026-27/001 (business initials + FY + sequence).
— 0425-0001 (MMYY + sequence, resets monthly).
InvoiceForge auto-generates the next number based on your chosen pattern — yearly reset, monthly reset, or continuous — so you never duplicate or skip a number.
Download free GST invoice templates
InvoiceForge ships with 5 professionally designed templates: Classic, Modern, Minimal, Professional, and Creative. Each template is available in 6 colour variations and works on A4 or A5 paper.
Every template automatically includes your logo, digital signature, stamp, bank details, UPI QR code with locked amount, HSN table, tax breakup, and amount in words (in English or your regional language).
You can fill in the data online, download as PDF, share via WhatsApp or email in one tap. No watermark. No signup required to download your first invoice.