taxInvoice.appGST invoice format: every mandatory field, explained
Short answer: A GST tax invoice must show the supplier's name, address and GSTIN; a unique consecutive invoice number of up to 16 characters; the date; the recipient's details (and GSTIN if registered); HSN/SAC, description, quantity and taxable value per item; the GST rate and amount split into CGST+SGST or IGST; place of supply; whether reverse charge applies; and a signature.
A GST tax invoice is the document a registered supplier issues for a taxable supply. The required contents are set by Rule 46 of the CGST Rules, 2017. Missing fields can cost your buyer their input tax credit, so they matter.
Mandatory fields
| # | Field | Notes |
|---|---|---|
| 1 | Supplier name, address and GSTIN | Check the GSTIN with the GSTIN validator |
| 2 | Invoice number | Max 16 characters; letters, digits, - and /; consecutive and unique per financial year |
| 3 | Date of issue | |
| 4 | Recipient name, address and GSTIN | GSTIN only if the recipient is registered |
| 5 | Delivery address and state for unregistered buyers | Required when the value is Rs. 50,000 or more |
| 6 | HSN code (goods) or SAC code (services) | Number of digits depends on your turnover |
| 7 | Description, quantity and unit | |
| 8 | Total value and taxable value | Taxable value after discounts |
| 9 | GST rate and amount | CGST + SGST for same-state supplies, IGST for inter-state (which one?) |
| 10 | Place of supply with state name | Required for inter-state supplies |
| 11 | Whether tax is payable on reverse charge | |
| 12 | Signature or digital signature |
Example layout
- Title “Tax Invoice”, invoice number and date at the top.
- Seller block (with GSTIN and state) and buyer block side by side.
- Item table: description, HSN/SAC, quantity, rate, taxable value, GST rate.
- Totals: taxable value, CGST and SGST (or IGST), round-off, grand total.
- Total in words, tax summary by rate, signature.
The GST invoice generator lays this out for you and checks each field as you type.
Related rules worth knowing
- E-invoicing: businesses above the e-invoicing turnover threshold must report B2B invoices to the Invoice Registration Portal and print the IRN and QR code. Check the current threshold for your business.
- Bill of supply: composition dealers and suppliers of exempt goods issue a bill of supply instead.
- Small retail sales: a consolidated daily invoice is allowed for very small sales to unregistered buyers when the buyer does not ask for an invoice.
Free tools for this
Frequently asked questions
How long can a GST invoice number be?
Up to 16 characters, using letters, digits, hyphens and slashes, unique and consecutive within a financial year (for example INV/26-27/001).
How many copies of a GST invoice are needed?
For goods, three: original for the recipient, duplicate for the transporter and triplicate for the supplier. For services, two: original for the recipient and duplicate for the supplier.
Is a signature mandatory?
Yes, a signature or digital signature of the supplier or an authorised representative is required. E-invoices authenticated on the government portal are an exception.