The GST law splits tax into two cases depending on where the supply happens.
Intra-state (same-state)
Customer's state == Your business state → split GST into two equal halves:
- CGST to the central government
- SGST (or UTGST) to your state government
A 18% GST rate becomes 9% CGST + 9% SGST on the invoice.
Inter-state (different states)
Customer's state ≠ Your business state → one combined component:
- IGST to the central government, later apportioned
A 18% GST rate stays 18% IGST on the invoice.
The "place of supply" wrinkle
The customer's billing state isn't always the place of supply. For services delivered to a specific location (e.g. on-site consultancy at a client site in another state), the place of supply is the location of service performance — which can differ from the customer's billed state.
Ketpy Book defaults place-of-supply to the customer's state on customer setup, but lets you override per-invoice for service deliveries that happen elsewhere.
What this means for invoice templates
Lite uses one fixed PDF template. Pro lets you pick from five professional templates — and any template you choose renders the right tax breakup automatically. You don't pick "an IGST template" vs "a CGST/SGST template".