What Is GST-Compliant Invoicing? A Complete Checklist for 2026
A GST-compliant invoice isn't a style choice — it's a legal document, and the CGST Act plus Rule 46 spell out exactly what it must contain. Miss a field, and you don't just risk an untidy invoice: your customer's input tax credit claim can be denied on the strength of your mistake, not theirs.
The checklist
- Invoice number and date — consecutive, unique per financial year, generated in one series with no gaps (see GST Rule 46(b) explained for exactly how strict this is).
- Your legal name, address, and GSTIN.
- Customer's name, address, and GSTIN (if registered) — or just name and address for an unregistered customer under a set value.
- HSN or SAC code for every line item — see HSN and SAC codes explained.
- Description, quantity, and unit for goods; description alone for services.
- Taxable value per line, before tax.
- GST rate and amount, split correctly into CGST+SGST or IGST — see how the split actually works.
- Place of supply, especially when it differs from the customer's billing address — this is what actually decides the CGST+SGST/IGST split, not just the customer's state on file. See place of supply rules explained.
- Signature (physical or digital) of the supplier or an authorised representative.
Where small businesses actually slip up
It's rarely the big fields. It's usually one of these:
- A skipped or reused invoice number — often from editing a mistake in a spreadsheet instead of issuing a fresh number. See common GST invoice mistakes that trigger a compliance notice.
- Wrong place of supply — billing a client's registered office in one state while actually delivering the service in another.
- A generic or wrong HSN/SAC code copied from a template instead of looked up properly.
- Invoicing without a valid GSTIN on file for a customer who claims to be registered — see what happens if you invoice without a valid GSTIN.
None of this is exotic — it's the same nine fields on every compliant invoice, checked the same way every time. That's exactly the kind of thing worth having software enforce rather than remembering manually. The official reference for the underlying rule is the GST portal itself, under the CGST Rules.