CGST vs SGST vs IGST: Which Applies to Your Invoice

GST is a single tax, but it's collected under three heads — CGST, SGST and IGST. Which one you charge doesn't change how much tax applies; it changes who collects it and how it's recorded. Pick the wrong head on an invoice and you'll be fixing it later, so let's make it simple.

The three heads

• CGST — Central GST, collected by the central government.
• SGST — State GST, collected by the state government where the supply happens.
• IGST — Integrated GST, collected by the centre on inter-state supplies and then apportioned with the destination state.

The one rule that decides it: place of supply

Compare the supplier's state with the place of supply (usually the customer's state):

• Same state → it's an intra-state supply. Split the GST equally into CGST and SGST. An 18% supply becomes 9% CGST + 9% SGST.
• Different states → it's an inter-state supply. Charge the whole rate as IGST — the full 18%.

A worked example

You're in Karnataka and sell services worth ₹1,000 at 18%:

• Customer in Karnataka: ₹90 CGST + ₹90 SGST = ₹180 tax, total ₹1,180.
• Customer in Maharashtra: ₹180 IGST, total ₹1,180.

Same ₹180 of tax either way — only the split differs. You can check any amount with the GST calculator.

Why it matters

The heads flow into your returns and your customer's input tax credit. Charge CGST/SGST on what was really an inter-state supply (or vice versa) and the credit can be mismatched, leading to notices and rework. It's a small detail with outsized consequences.

Special cases to watch

• Place of supply for services isn't always the customer's billing address — specific rules apply (e.g. for immovable property or events).
• Union territories use UTGST in place of SGST.
• Exports are treated as inter-state and are typically zero-rated.

Let the tool handle it

You don't have to decide the head on every line manually. The Billzora invoice generator compares the two states and applies CGST + SGST or IGST automatically, so your invoices come out right the first time. New to invoicing? Start with how to create a GST-compliant invoice.