"Rs 10,000" means two different things depending on whether GST is included. At 18% the gap is Rs 1,800 on that one line — enough to matter, and enough to argue about.
The two bases
GST exclusive — the price quoted is the taxable value, and GST is added on top. A quote of Rs 10,000 exclusive at 18% costs Rs 11,800.
GST inclusive — the price quoted already contains the GST. A quote of Rs 10,000 inclusive at 18% contains Rs 1,525.42 of tax, leaving a taxable value of Rs 8,474.58.
The seller receives Rs 10,000 in one case and Rs 8,474.58 in the other. Same headline number, materially different economics.
Converting between them
Exclusive to inclusive: inclusive = exclusive x (1 + rate)
Rs 10,000 at 18% becomes Rs 11,800.
Inclusive to exclusive: exclusive = inclusive / (1 + rate)
Rs 10,000 at 18% becomes Rs 8,474.58, with Rs 1,525.42 of GST.
The tax contained in an inclusive price is inclusive x rate / (100 + rate).
Which basis is normal where
Business to business quoting is usually exclusive. Registered buyers typically recover the GST as input tax credit, so the exclusive figure is the one that describes their real cost, and it is the number both sides want to negotiate.
Business to consumer pricing is usually inclusive. Retail customers cannot recover GST, so the price on the shelf is the price they pay. Displayed retail prices are expected to be the amount payable.
Mixing conventions between the two contexts is where disputes start.
How to avoid the argument
- Say which basis you mean, every time. Write "Rs 10,000 plus GST" or "Rs 10,000 inclusive of GST" rather than "Rs 10,000".
- Show the rate in the quote, not just the word GST.
- Show the arithmetic in proposals: taxable value, rate, tax amount, total.
- Ask when you receive a quote that does not say. It costs one email and saves a renegotiation.
- Watch contract clauses. A contract silent on GST treatment is a contract with an argument waiting in it.
A worked comparison
A supplier quotes Rs 1,00,000 for a service at 18%.
If exclusive: taxable value Rs 1,00,000, GST Rs 18,000, payable Rs 1,18,000.
If inclusive: taxable value Rs 84,745.76, GST Rs 15,254.24, payable Rs 1,00,000.
The difference to the buyer's cash outflow is Rs 18,000. For a registered buyer who recovers the credit, the real difference is the Rs 15,254.24 of value the supplier gives up.
For registered buyers
If you recover input tax credit, compare quotes on the exclusive figure. A supplier quoting Rs 11,500 inclusive may be cheaper than one quoting Rs 10,000 exclusive once you strip the tax out of both — and the headline numbers suggest the opposite.
Where to go next
- Read how to calculate GST for the formulas.
- Read CGST, SGST and IGST explained.
- Read GST rates in India.
- Use the GST calculator, which works in both directions.