MathsICSE Class 10 · Goods and Services Tax (GST)

GST with Discount: Marked Price, Taxable Value and Amount Paid (ICSE Class 10)

Updated 15 October 2026 · Fact-checked

When a discount is given, GST is charged on the price after the discount, not on the marked price. So take the discount off the marked price to get the taxable value, then add GST at the given rate: amount paid = marked price × (1 − d/100) × (1 + r/100).

Take the discount off first; GST is charged only on the taxable value (₹900), not on the marked price (₹1000).

Illustration drawn for QuestionBuddy.

Understand GST with Discount

Shops rarely sell at the marked price. A discount lowers the selling price, and GST is then charged on what the customer actually pays for the goods, the taxable value. The order of work never changes:

$Marked (list) price minus discount Taxable value plus GST Amount paid .$

If the marked price is $M$ , the discount is $d %$ and the GST rate is $r %$ , then

$V = M (1 - \frac{d}{100}), A = V (1 + \frac{r}{100}) = M (1 - \frac{d}{100}) (1 + \frac{r}{100}) .$

Why the order matters for the tax, not the total. Because multiplication can be done in any order, $M \times 0.9 \times 1.1$ equals $M \times 1.1 \times 0.9$ . But the GST is a definite amount: $r %$ of $V$ . If you add tax on the marked price and then take the discount off, the tax shown is wrong, even if the final total happens to agree. ICSE questions ask for the GST, the CGST or the SGST separately, so you must find $V$ first.

Kinds of discount.

A percentage discount: $V = M (1 - \frac{d}{100})$ .
A flat discount of ₹ $k$ : $V = M - k$ .
Successive discounts of $d_{1} %$ and $d_{2} %$ : $V = M (1 - \frac{d _{1}}{100}) (1 - \frac{d _{2}}{100})$ . Two discounts of 20% and 5% are not the same as 25%; they make 24%.
A conditional discount, such as '5% off an item if 12 or more are bought': check the quantity of each item before applying it. The examiners reported that many candidates missed exactly this condition in 2025 Q7(iii).

Inverse cases. If the amount paid $A$ is known, first find $V = \frac{100 A}{100 + r}$ . Then compare $V$ with the marked price to get the discount ( $M - V$ , and as a percentage of $M$ ), or divide by $(1 - \frac{d}{100})$ to get the marked price.

Profit and loss with GST. The CISCE syllabus includes problems with profit, loss and cost price. The shopkeeper's profit is measured on the taxable value (his selling price), because the GST he collects belongs to the government. So profit = $V$ − cost price, and profit % is taken on the cost price.

GST with Discount: formulas to remember

Taxable value after a percentage discount: $V = M (1 - \frac{d}{100})$; $M$ = marked price, $d %$ = discount.
Amount paid: $A = V (1 + \frac{r}{100})$; $r %$ = GST rate (CGST + SGST together).
Successive discounts: $V = M (1 - \frac{d _{1}}{100}) (1 - \frac{d _{2}}{100})$; Not $M (1 - \frac{d _{1} + d _{2}}{100})$ .
Taxable value from the amount paid: $V = \frac{100 \times A}{100 + r}$; First step of every inverse question.
Discount percentage: $d = \frac{M - V}{M} \times 100$; Discount is always a percentage of the marked price.
Profit of the seller: $Profit = V - CP, Profit % = \frac{V - CP}{CP} \times 100$; GST is not part of the seller's profit.

How to solve GST with Discount questions

Every GST-with-discount question is a chain of three prices. Decide which price you know and walk along the chain.

1Write the chain: Marked price → (discount) → Taxable value → (GST) → Amount paid.
2Mark which price is given and which is asked; also note any condition on the discount.
3Going forward: subtract the discount from $M$ to get $V$ , then multiply by $(1 + \frac{r}{100})$ .
4Going backward from the amount paid: $V = \frac{100 A}{100 + r}$ ; then $M = \frac{100 V}{100 - d}$ , or $d = \frac{M - V}{M} \times 100$ .
5If CGST or SGST is asked, find GST $= \frac{r}{100} \times V$ and halve it.
6For profit or loss, compare $V$ (not $A$ ) with the cost price.
7State the answer with ₹ and units, rounding only as instructed.

GST with Discount in real life

Each concept, met in an everyday situation. Read the situation, try the problem, then check the solution. The one-line hook is what to remember.

Discount first, then GST

Suppose a store's festival sale offers 25% off a jacket marked ₹3,200, and GST on the jacket is 12%.

Find the taxable value, the GST and the amount you pay. How much would you have paid with no sale?

Try it first, then show the solutionSolution

Taxable value $= 3200 \times 0.75 = 2400$ .
GST $= 12%$ of $2400 = 288$ ; amount paid $= 2400 + 288 = 2688$ .
With no sale: $3200 \times 1.12 = 3584$ .

Answer: Taxable value ₹2,400, GST ₹288, you pay ₹2,688 (instead of ₹3,584). The sale also cut the tax, from ₹384 to ₹288.

Memory hook: A discount saves you twice: on the price and on the tax.

Checking whether you can afford a discounted article

Imagine you have saved ₹2,000 and see headphones marked ₹2,250 with 20% off. The GST rate is 18%.

Can you buy the headphones with your savings? If not, how much more do you need?

Try it first, then show the solutionSolution

Taxable value $= 2250 \times 0.80 = 1800$ .
Amount paid $= 1800 \times 1.18 = 2124$ .
$2124 - 2000 = 124$ .

Answer: No. The headphones cost ₹2,124 with GST, so you need ₹124 more.

Memory hook: Read the price tag, take off the discount, then add the tax before you reach for your wallet.

Tricks to remember GST with Discount

Short memory aids. Say each one aloud once, then use it on a question the same day.

M-V-A: Marked, Value, Amount
Always walk M → V → A. Discount lives between M and V; GST lives between V and A.
Use it when: Setting up any forward or inverse question.
Two discounts never just add
20% then 5% is $0.8 \times 0.95 = 0.76$ , a 24% discount, not 25%.
Use it when: Successive discount questions.
Read the small print
Circle every 'if' in a bill question ('if 10 or more are bought'). An 'if' changes one row of the bill.
Use it when: Conditional discounts, as in 2025 Q7(iii).
Profit stops at V
The shopkeeper's money stops at the taxable value; the GST passes through his hands to the government.
Use it when: Profit and loss questions with GST.

GST with Discount: solved examples

Ordered from board level to HOTS. Try each one before you open the solution.

Example 1: Amount paid after a discount · 1 mark · MCQBoard level

The marked price of an article is ₹5,000. A discount of 10% is given and GST is charged at 12%. The amount paid by the customer is:
(a) ₹5,040
(b) ₹5,600
(c) ₹4,500
(d) ₹5,000

Try it first, then show the solutionSolution

Taxable value $= 5000 \times 0.9 = 4500$ .
Amount paid $= 4500 \times 1.12 = 5040$ .

Answer: (a) ₹5,040

Example 2: CGST after a discount · 3 marks · Short answerBoard level

A laptop is marked at ₹45,000. The shop gives a discount of 8% and the sale is intra-state with GST at 18%. Find (a) the taxable value, (b) the CGST, (c) the amount paid by the customer.

Try it first, then show the solutionSolution

(a) Discount $= 8%$ of $45000 = 3600$ ; taxable value $= 45000 - 3600 = 41400$ .
(b) CGST $= 9%$ of $41400 = 3726$ .
(c) Amount paid $= 41400 + 3726 + 3726 = 48852$ .

Answer: (a) ₹41,400 (b) ₹3,726 (c) ₹48,852

Example 3: Successive discounts · 3 marks · Short answerHarder board level

An article marked at ₹6,000 is sold after two successive discounts of 20% and 5%. GST is charged at 12%. Find the GST and the amount paid. What single discount is equal to the two discounts?

Try it first, then show the solutionSolution

After 20% off: $6000 \times 0.8 = 4800$ . After a further 5% off: $4800 \times 0.95 = 4560$ = taxable value.
GST $= 12%$ of $4560 = 547.20$ ; amount paid $= 4560 + 547.20 = 5107.20$ .
Single discount $= \frac{6000 - 4560}{6000} \times 100 = 24%$ .

Answer: GST ₹547.20; amount paid ₹5,107.20; the single equivalent discount is 24%.

Example 4: A bill with a conditional discount · 4 marks · Short answerHarder board level

A shop gives a 5% discount on an item only when 12 or more of that item are bought. A customer buys 12 packets of item P at ₹85 each (GST 12%) and 5 boxes of item Q at ₹240 each (GST 18%). Find the bill amount, rounded off to the nearest ₹10.

Try it first, then show the solutionSolution

P: $12 \times 85 = 1020$ ; 12 are bought, so 5% off: taxable value $= 1020 \times 0.95 = 969$ ; GST $= 12%$ of $969 = 116.28$ .
Q: $5 \times 240 = 1200$ ; fewer than 12, so no discount; GST $= 18%$ of $1200 = 216$ .
Bill $= 969 + 116.28 + 1200 + 216 = 2501.28$ .
Rounded to the nearest ₹10: ₹2,500.

Answer: ₹2,501.28, which is ₹2,500 to the nearest ₹10.

Example 5: Finding the discount and the profit · 4 marks · Short answerHOTS / competency

A shopkeeper buys an article for ₹4,000 and marks it 25% above his cost price. He gives a discount so that the customer pays ₹4,956 including GST at 18%. Find (a) the discount percentage, (b) the shopkeeper's profit percentage.

Try it first, then show the solutionSolution

Marked price $= 4000 \times 1.25 = 5000$ .
Taxable value $= \frac{100 \times 4956}{118} = 4200$ .
(a) Discount $= 5000 - 4200 = 800$ , that is $\frac{800}{5000} \times 100 = 16%$ .
(b) Profit $= 4200 - 4000 = 200$ , that is $\frac{200}{4000} \times 100 = 5%$ .

Answer: (a) 16% (b) 5%

Example 6: Case study: comparing two offers · 4 marks · Case-basedHOTS / competency

A television is sold by two shops in the same city, both charging GST at 18%.
Shop A: marked ₹12,000, discount 15%.
Shop B: marked ₹11,500, a flat ₹1,000 off and then a further 5% off.
(a) Find the amount paid at each shop.
(b) Which shop is cheaper, and by how much?
(c) Show that the difference in (b) is 1.18 times the difference in the taxable values.

Try it first, then show the solutionSolution

Shop A: taxable value $= 12000 \times 0.85 = 10200$ ; amount $= 10200 \times 1.18 = 12036$ .
Shop B: $11500 - 1000 = 10500$ ; then $10500 \times 0.95 = 9975$ = taxable value; amount $= 9975 \times 1.18 = 11770.50$ .
(b) Shop B is cheaper by $12036 - 11770.50 = 265.50$ .
(c) Difference in taxable values $= 10200 - 9975 = 225$ , and $1.18 \times 225 = 265.50$ , because each amount is 1.18 times its taxable value.

Answer: (a) Shop A ₹12,036; shop B ₹11,770.50. (b) Shop B, by ₹265.50. (c) $1.18 \times 225 = 265.50$ .

Where students lose marks in GST with Discount

The slips examiners see most often, and what to write instead.

Mistake: Charging GST on the marked price
The goods are sold at the discounted price, so that is the taxable value.
Wrong working
GST $= 18%$ of $45000 = 8100$ .
Right working
GST $= 18%$ of $41400 = 7452$ (after the 8% discount).
Do this: Write 'Taxable value = …' on its own line before any tax.
Usually costs: Usually every mark after the first step.
Mistake: Adding successive discounts
The second discount is on the already reduced price.
Wrong working
20% and 5% off ₹6,000: $6000 \times 0.75 = 4500$ .
Right working
$6000 \times 0.8 \times 0.95 = 4560$ .
Do this: Apply discounts one after the other.
Usually costs: The answer mark and every mark that depends on it.
Mistake: Missing a discount condition
Conditions like '10 or more articles' apply only to some rows of a bill.
Wrong working
No discount on 12 packets although '5% off on 12 or more' was stated.
Right working
$1020 \times 0.95 = 969$ for that row only.
Do this: Check the quantity of each row against the condition before working.
Usually costs: The examiners named this error for 2025 Q7(iii), a 4-mark question.
Mistake: Working back by subtracting r% of the amount paid
The tax was r% of the taxable value, not of the amount paid.
Wrong working
₹4,956 includes 18% GST, so $V = 4956 - 0.18 \times 4956 = 4063.92$ .
Right working
$V = \frac{100 \times 4956}{118} = 4200$ .
Do this: Divide by $(1 + \frac{r}{100})$ ; never subtract $r %$ of $A$ .
Usually costs: All the marks of an inverse question.

Exam tips

Show the taxable value as a separate line; it carries a method mark even if your final arithmetic slips.
In 2025 Q7(iii) a bill had a 5% discount for 10 or more articles and a total rounded to the nearest ₹10; the examiners reported candidates who missed the discount condition and who did not round off.
When a question says 'find the discount' give both the amount and the percentage unless only one is asked.
In profit questions, write 'GST is not included in the shopkeeper's profit' and compare the taxable value with the cost price.
Check an inverse answer by working forward: your marked price, discount and rate must give back the amount paid.

Practice questions on GST with Discount

Write each answer on paper first. Open the hint only if you are stuck, and the answer only when you have finished.

Q1 · 1 mark · MCQBoard level
When a discount is given on an article, GST is charged on:
(a) the marked price
(b) the price after the discount
(c) the discount
(d) the cost price of the shopkeeper
Hint
GST is charged on the taxable value.
Answer
(b) the price after the discount.
Q2 · 3 marks · Short answerBoard level
A bicycle is marked at ₹2,500. It is sold at a discount of 12% in an intra-state sale with GST at 5%. Find the SGST and the amount paid.
Hint
SGST is 2.5% of the taxable value.
Answer
Taxable value = 2500 × 0.88 = ₹2,200. SGST = 2.5% of 2200 = ₹55. Amount paid = 2200 + 55 + 55 = ₹2,310.
Q3 · 3 marks · Short answerHarder board level
The list price of a cooler is ₹8,000. A customer pays ₹8,496 including GST at 18%. Find the percentage discount given.
Hint
Find the taxable value from ₹8,496 first.
Answer
Taxable value $= \frac{100 \times 8496}{118} = 7200$ . Discount $= 800$ , that is 10%.
Q4 · 3 marks · Short answerHarder board level
After a discount of 10%, a customer pays ₹3,024 for an article, including GST at 12%. Find the marked price of the article.
Hint
Work backwards: amount → taxable value → marked price.
Answer
Taxable value $= \frac{100 \times 3024}{112} = 2700$ ; marked price $= \frac{2700}{0.9} = ₹3, 000$ .
Q5 · 1 mark · Assertion-reasonHarder board level
Assertion (A): An article marked ₹1,000 is sold at a discount of 10% with GST at 10%. The amount paid is ₹1,000.
Reason (R): GST is charged on the price after the discount.
(a) (A) is true and (R) is false.
(b) (A) is false and (R) is true.
(c) Both (A) and (R) are true, and (R) is the correct explanation for (A).
(d) Both (A) and (R) are true, but (R) is not the correct explanation for (A).
Hint
Compute $1000 \times 0.9 \times 1.1$ .
Answer
(b). The amount is $900 \times 1.1 = ₹990$ , not ₹1,000, so (A) is false; (R) is true.
Q6 · 4 marks · Short answerHOTS / competency
A shopkeeper buys an article for ₹2,400. He wants a profit of 20% after giving a discount of 10% on the marked price. GST is 18%. Find (a) the marked price, (b) the amount the customer pays.
Hint
Profit is on the taxable value: $V = 1.2 \times 2400$ .
Answer
(a) $V = 2400 \times 1.2 = 2880$ ; marked price $= \frac{2880}{0.9} = ₹3, 200$ . (b) $2880 \times 1.18 = ₹3, 398.40$ .
Q7 · 4 marks · Short answerHarder board level
An article is marked ₹3,000 and GST is 10%. Ravi works out 'add 10% GST, then take 10% off'; Sana works out 'take 10% off, then add 10% GST'. (a) Show that both get the same amount to pay. (b) Whose GST figure is correct, and why?
Hint
Compare the tax each of them writes down, not just the totals.
Answer
(a) Ravi: $3000 \times 1.1 = 3300$ , then $3300 \times 0.9 = 2970$ . Sana: $2700 \times 1.1 = 2970$ . Both ₹2,970. (b) Sana's GST of ₹270 (10% of ₹2,700) is correct; Ravi's ₹300 is 10% of the marked price, but GST is charged on the price after the discount.

Test your recall

Answer in your head or on paper first, then open the card. Pulling an answer out of memory makes it stick far better than re-reading.

1.Marked price ₹1,200, discount 25%. What is the taxable value?Show answer
₹900.
2.Taxable value ₹900, GST 12%. What is the amount paid?Show answer
₹1,008.
3.What single discount equals successive discounts of 10% and 10%?Show answer
19%, since $0.9 \times 0.9 = 0.81$ .
4.An amount of ₹1,180 includes GST at 18%. What is the taxable value?Show answer
₹1,000.
5.Is GST part of a shopkeeper's profit?Show answer
No. Profit = taxable value − cost price; the GST is paid to the government.
6.A flat discount of ₹300 on ₹2,300, then 5% GST. Amount paid?Show answer
$2000 \times 1.05 = ₹2, 100$ .

GST with Discount: frequently asked questions

Is GST calculated before or after the discount?

After. GST is charged on the taxable value, which is the price the article is actually sold for after the discount.

How do I find the marked price if I know the amount paid including GST?

First divide the amount paid by (1 + r/100) to get the taxable value. Then divide the taxable value by (1 − d/100) to get the marked price.

Are two discounts of 10% the same as one discount of 20%?

No. The second 10% is taken off the reduced price, so together they equal a single discount of 19%.

Does the ICSE syllabus include profit and loss with GST?

Yes. The CISCE 2027 syllabus lists computation of tax including problems on discounts, list price, profit, loss and cost price, with inverse cases.