Which document to issue under GST by registration status — tax invoice, bill of supply, or kaccha bill

GST does not use one universal document — which one a supplier issues depends on their registration status and the nature of the supply. The decision tree above resolves the choice between a tax invoice, a bill of supply, and the informal kaccha bill, starting from a single question: is the supplier GST-registered?

The first branch is **registered + regular scheme + taxable supply**. Here Section 31 of the CGST Act requires a **tax invoice** carrying the full Rule 46 particulars — the supplier charges GST, shows the CGST/SGST or IGST split, and the buyer can claim input tax credit. This is the document most B2B transactions run on. The second branch covers a registered supplier who is either under the **composition scheme** or supplying **exempt or nil-rated goods**. Such a supplier cannot collect GST, so Section 31(3)(c) and Rule 49 direct them to issue a **bill of supply** instead — same commercial detail, but no tax line and no ITC for the buyer.

The third branch is the **unregistered supplier below the registration threshold**. Without a GSTIN there is no GST to charge, so the supplier issues a plain invoice or bill of supply with no tax component. This is legitimate — being below the threshold is not the same as being non-compliant. The kaccha bill sits outside all three branches: it is an informal slip with no GSTIN, no tax split, and no return trail, and the GST law does not recognise it as any kind of statutory document. Issuing a kaccha bill where a tax invoice is required is a breach; relying on one as a buyer forfeits ITC.

The trap most businesses fall into is treating "bill of supply" and "kaccha bill" as the same thing because neither shows GST. They are not. A bill of supply is a proper GST document issued by a registered composition or exempt-goods supplier, with its own format under Rule 49; a kaccha bill is the absence of any GST document. The registration status of the supplier — not the look of the paper — is what decides which branch you are on.