Guides · GST
GST invoice format and mandatory fields
A GST tax invoice does not have a single legally fixed layout, but it does have a fixed set of mandatory fields. Getting the format right means every required field is present and the tax is split correctly.
The mandatory fields on a GST invoice
Every GST tax invoice must show: the supplier's name, address and GSTIN; a consecutive, financial-year-unique invoice number and the date of issue; the recipient's name, address and GSTIN where registered; the HSN or SAC code; the description, quantity and unit; the total taxable value after any discount; the tax rate and amount by head — CGST and SGST, or IGST; the place of supply for inter-state trade; and whether tax is payable on reverse charge.
For goods, the invoice is generally prepared in triplicate — original for the recipient, duplicate for the transporter, triplicate for the supplier. For services it is prepared in duplicate.
Where formats go wrong
The common mistakes are a broken invoice-number series, a missing or wrong HSN code, and the wrong tax split — charging CGST and SGST on an inter-state supply, or IGST on an intra-state one. The place of supply is what decides which split is correct.
A signature or digital signature of the supplier or an authorised person is also required for a valid tax invoice.
How Lekha keeps the format correct
Lekha generates GST-compliant delivery challans and tax invoices against a purchase order, with HSN, place of supply, and the right CGST/SGST or IGST split computed live, and gap-free financial-year numbering.
The place of supply drives the CGST/SGST-versus-IGST decision automatically, and the number series stays consecutive for the financial year, so the format is right on the first issue.
Questions
- Is there one legal GST invoice format?
- No single layout is mandated, but a fixed set of fields is. Any format that carries all the mandatory fields correctly is valid.
- Do I need to sign a GST invoice?
- Yes. A valid tax invoice needs the signature or digital signature of the supplier or an authorised signatory.
- How many copies of a GST invoice are needed?
- For goods, generally three — recipient, transporter, and supplier. For services, two — recipient and supplier.
This guide is general information, not legal or tax advice. Confirm the current rules and your own circumstances for any specific case.