GST & invoices

CGST + SGST or IGST: what one invoice actually prints

The rate on a line is one question. Which column that rupee lands in is another. After GST 2.0 — 56th Council, notified for 22 September 2025 — most everyday invoices still print 5% or 18%, with a 40% peak on notified luxury and sin lines. That percentage is the same whether the supply is intra-state or inter-state. What changes is the label: CGST plus SGST (or UTGST) at half each, or IGST at the full rate. I built the GST calculator so you can see that split without a login. The calculator will not know whether your warehouse and your customer share a state. Place of supply is a legal test in the IGST Act, not “where I clicked calculate.”

Source for rates: CBIC GST goods and services rates. Last pass for the calculator’s default list: GST 2.0 from the 56th Council, 22 September 2025, with later tariff tweaks in Notification 01/2026-Central Tax (Rate). Place of supply lives in the IGST Act, 2017 — sections 10 (goods) and 12 (services) — not in a news carousel. If a newer notification exists the day you read this, the notification wins. I do not invent HSN lists here. You bring the rate; the box does the arithmetic.

The split is not a style choice

Intra-state supply: the same GST rupees split equally into CGST and SGST. Union territory without a legislature uses UTGST in the state slot. Inter-state supply, including most supplies into a different state and supplies treated as inter-state (SEZ is the classic one), puts the same rupees into IGST. Imports into a state are an IGST story at the border, not a CGST/SGST pair you type because the importer’s office is down the road. Composition dealers do not get to pick this menu as if they were regular taxpayers. Reverse charge on specified services still exists; neither this note nor the calculator will flash a warning.

The rate did not change when you flipped the radio. ₹1,800 of 18% on ₹10,000 is still ₹1,800. Intra-state prints CGST ₹900 and SGST ₹900. Inter-state prints IGST ₹1,800. Input tax credit follows those columns into your ledger. Credit a CGST line against an IGST liability because “GST is GST” and you will meet a mismatch, not a rounding debate.

Place of supply is not the warehouse pin code

For goods that move, the usual test is where the movement terminates for delivery to the recipient — IGST Act section 10. For services to a registered person, the usual test is the location of the recipient — section 12. Those sentences hide a decade of disputes. Bill-to-ship-to is the one that wrecks clean Slack advice. If a supplier delivers goods to B on the direction of A, section 10(1)(b) treats A as the recipient and puts place of supply at A’s principal place of business. The truck ending in Karnataka does not automatically make Karnataka the place of supply. E-commerce is the opposite trap: the billing entity and the warehouse share Pune, the customer is in Bengaluru, and someone still splits CGST/SGST because “we are a Maharashtra company.” The customer’s delivery state is what the place-of-supply rule cares about for that sale, not the city on the GSTIN letterhead.

I will not pretend a blog post is a classification opinion. Goods versus restaurant service, installation versus supply, OIDAR versus local support — CBIC circulars and advance rulings exist because those fights are real. The calculator will happily tax the wrong story at the right rate. That is a feature of a line-check box, not a bug.

Worked example: exclusive 18%, same state

Taxable value ₹50,000. Rate 18% — the GST 2.0 working default, not a guess at an HSN. GST = ₹9,000. Invoice total = ₹59,000. Supplier and recipient both in Maharashtra: CGST ₹4,500, SGST ₹4,500, IGST zero. Open the calculator, exclusive, 18%, intra-state. If your software disagrees by ₹0.01, it rounded a line before the total. I show two decimals and stop. This is the textbook intra-state case. It is also the case people copy onto an inter-state shipment because the PDF template had two tax columns.

Worked example: e-commerce pack, customer in another state

Sticker ₹2,100, tax included, 5% merit. Taxable value = 2100 / 1.05 = ₹2,000. GST = ₹100. Warehouse and billing GSTIN in Pune. Customer delivery in Bengaluru. The ₹100 is IGST, not CGST ₹50 plus SGST ₹50. Inclusive mode is algebra: if you type the exclusive figure into inclusive mode you understate tax by rate/(100+rate). The place-of-supply error is worse than the algebra error. Credit notes and marketplace TCS will not save a year of intra-state invoices that should have been IGST. Related rate story: what 5%, 18%, and 40% actually sit on after GST 2.0.

Worked example: bill-to-ship-to

Supplier in Gujarat. Invoice billed to a registered buyer whose principal place of business is in Maharashtra. Goods delivered, on that buyer’s direction, to a warehouse in Karnataka. Under section 10(1)(b), place of supply is Maharashtra — the third person’s principal place of business — not Karnataka where the truck doors opened. Gujarat to Maharashtra is inter-state. Exclusive ₹80,000 at 18% is GST ₹14,400, all IGST, total ₹94,400. If someone “fixes” the invoice to CGST/SGST because the warehouse is “south,” they invented a same-state supply that the Act does not see. Confirm against the IGST Act and your CA, not against the map pin that looks obvious in a warehouse WhatsApp group.

What this note adds that the calculator does not

The tool is a line check: type amount, pick rate, pick intra or inter, see columns. This note is why that radio button is a legal fact, not a display theme. SEZ supplies are treated as inter-state even when the unit is in the same state as the supplier. Union territories swap SGST for UTGST; the half-and-half arithmetic is the same. Debit notes follow the original supply’s place of supply, which is how a 2024 intra-state 12% line still haunts a 2026 credit. E-invoicing IRN generation and GSTR-1 live in GSTN. I will not look up your HSN. CBIC’s rate finder is the page for “what percentage sits on this item.”

If you only needed the 18% half-and-half on ₹10,000, the calculator page already has it. Use this note when the warehouse, the GSTIN, and the delivery address disagree, and you are about to pick a column because it is the one your template printed last quarter.