Reverse Tax Calculator

Q: What is a reverse tax calculator?

A reverse tax calculator finds the original price before tax from a tax-inclusive (total) amount. Formula: Base Price = Total ÷ (1 + Tax%/100). GST Amount = Total − Base. Example: If you paid ₹1180 and GST is 18%, the base price = 1180 ÷ 1.18 = ₹1000, and GST = ₹180. This is also called reverse GST calculation or back-calculating tax.

Q: What are the current GST slabs in India (2025)?

As of September 2025 (GST 2.0), India has four main GST rates: 3% (gold and silver), 5% (essentials — food, medicines, EVs, insurance), 18% (standard goods and services — electronics, cement, apparel), and 40% (luxury and sin goods — aerated drinks, premium cars). The earlier 12% and 28% slabs have been removed.

Q: How do you use a reverse tax calculator to find price before GST?

Use the formula: Base Price = Total Price (with GST) ÷ (1 + GST%/100). GST Amount = Total − Base Price. Example: Total = ₹118 with 18% GST → Base = 118 / 1.18 = ₹100. GST Amount = ₹18. This reverse tax formula works for any tax percentage — just replace 18 with your rate.

Q: How do you add GST to a price?

Use the formula: Total (with GST) = Base Price × (1 + GST%/100). GST Amount = Total − Base. Example: Base = ₹1000, GST = 18% → Total = 1000 × 1.18 = ₹1180. GST Amount = ₹180.

Q: What is the difference between CGST, SGST, and IGST?

For intra-state (within same state) transactions, GST is split equally between CGST (Central GST) and SGST (State GST). For inter-state transactions, only IGST (Integrated GST) applies at the full rate. Example: 18% GST on intra-state sale = 9% CGST + 9% SGST. The total tax burden is the same either way.

Q: Where does GST calculation appear in competitive exams?

GST problems appear in SSC CGL, CHSL, IBPS, and Railway exams under the Arithmetic/Commercial Math chapter. Common question types: find the GST amount on a given price, find the original price when GST-inclusive price is given, and problems combining GST with profit/loss or discount.

Q: What is the GST rate on gold in India 2025?

Gold and silver attract a 3% GST rate in India as of 2025. This is a special rate specific to precious metals and is not part of the general GST slab structure (5%, 18%, 40%).

Reverse tax calculator: you know the final price with GST already included — find the original base price and exact tax amount.

Total Price (with GST) ₹

GST Rate

Please enter a valid price and GST rate (0–100%).

You know the base price before GST — find the final price and tax amount.

Base Price (ex-GST) ₹

GST Rate

Please enter a valid price and GST rate (0–100%).

How to Use

Choose Mode

Select Reverse GST if the price already includes tax, or Add GST if you have the base price.

Pick GST Slab

Click a slab button (3%, 5%, 18%, 40%) or type a custom rate. Enter the price.

Get Breakdown

Click Calculate to see the base price, GST amount, and CGST/SGST split with full working.

Frequently Asked Questions

What is a reverse tax calculator and when do you use it?

A reverse tax calculator works backwards from a tax-inclusive price to find the original base price and the tax amount. You use it when a bill or invoice already includes tax and you need to separate the two.
Common situations: checking if GST on a restaurant bill is correct, finding the ex-GST price on an e-commerce purchase, or verifying input tax credit amounts.

What are the current GST slabs in India (2025)?

As of September 2025 (GST 2.0 reform), India has four main rates:
3% — Gold & Silver
5% — Essentials (food, medicines, EVs, insurance)
18% — Standard goods & services (electronics, cement, apparel)
40% — Luxury & sin goods (aerated drinks, premium cars)
The older 12% and 28% slabs were removed in this reform.

How do you use a reverse tax calculator to find price before GST?

Base Price = Total ÷ (1 + GST%/100)
GST Amount = Total − Base Price
Example: Total = ₹1180, GST = 18% → Base = 1180 ÷ 1.18 = ₹1000, GST = ₹180.
Think of it as: the total is (100 + GST)% of base, so divide by that multiplier.

How do you add GST to a base price?

Total = Base × (1 + GST%/100)
GST Amount = Total − Base
Example: Base = ₹1000, GST = 18% → Total = 1000 × 1.18 = ₹1180, GST = ₹180.

What is the difference between CGST, SGST, and IGST?

For intra-state transactions (seller and buyer in same state), GST is split equally:
CGST (Central) = GST% / 2 + SGST (State) = GST% / 2
For inter-state transactions, only IGST applies at the full rate.
Example: 18% GST intra-state = 9% CGST + 9% SGST. Total burden is the same.

What is the GST rate on gold in India 2025?

Gold and silver attract 3% GST in India (2025). This is a special rate for precious metals — it is separate from the general slab structure. Making charges on gold jewellery attract 5% GST separately.

Where does GST calculation appear in competitive exams?

GST problems appear in SSC CGL, CHSL, IBPS PO, Clerk, and Railway exams under Commercial Math. Common types: find GST amount on a given price, find original price from GST-inclusive price, and problems combining GST with profit/loss or discount. The calculation is identical to percentage markup problems.

How to Use

Frequently Asked Questions

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