What is the Reverse GST?
When a price is quoted inclusive of GST, you cannot simply take 18% of it to find the tax — that overstates it. The tax is 18% of the base, which is smaller than the total.
For intra-state supplies GST splits equally into CGST and SGST; for inter-state it is a single IGST at the full rate.
Formula & worked example
GST = Inclusive amount − Base
Worked example: ₹11,800 inclusive of 18% GST → base = 11,800 / 1.18 = ₹10,000, so GST is ₹1,800 (CGST ₹900 + SGST ₹900). Taking 18% of ₹11,800 would wrongly give ₹2,124 — an error of ₹324.
How to use this reverse gst calculator
- Enter the total amount including GST.
- Select the applicable GST rate — 5% or 18% for almost everything since the 22 September 2025 reform, or 40% for selected sin and luxury goods.
- The base value is what you record as taxable turnover.
- CGST and SGST are each half the total for intra-state supplies.
Smart tips
- MRP in India is always GST-inclusive, so use reverse GST to find the base value for accounting.
- Never compute GST as a straight percentage of an inclusive price — always divide first.
- Input tax credit is claimed on the GST component, so extracting it correctly matters for your returns.
- For inter-state supply, the entire amount is IGST rather than split into CGST and SGST.
Frequently asked questions
How do I remove GST from a price?
Divide the inclusive amount by (1 + rate/100). For 18%, divide by 1.18 to get the base value.
Is MRP inclusive of GST?
Yes. Under legal metrology rules the MRP printed on a product is the maximum price inclusive of all taxes.
What is the difference between CGST, SGST and IGST?
Intra-state supplies split GST equally into CGST (central) and SGST (state). Inter-state supplies attract IGST at the full rate.
Why is 18% of the inclusive price wrong?
Because GST is charged on the base value, not the total. Taking 18% of the inclusive amount overstates the tax by about 18% of the tax itself.
Want the theory behind the numbers? Browse the Money Blog for worked guides.
Written by Gurjeet Singh, Sharpen Solutions. Last reviewed 15 Oct 2026. Sources: GST Council — 56th meeting: 5% merit rate, 18% standard rate, 40% special rate, in force 22 Sep 2025, GST Council — FAQs on the two-rate structure (Sep 2025). How we check these numbers.