AccountancyCBSE Class 11 · Depreciation, Provisions and Reserves

Straight Line and Written Down Value Methods Class 11: Formulas and Part-Year Depreciation

Updated 17 October 2026 · Fact-checked

Under the straight line method (SLM) the same depreciation is charged every year: (cost − scrap value) ÷ useful life, or a fixed percentage of original cost. Under the written down value method (WDV) a fixed percentage is applied to the book value at the start of each year, so depreciation falls year by year. For assets bought during the year, charge depreciation only for the months of use.

Under SLM the depreciation bar stays the same every year, but under WDV it shrinks because the rate is applied to a falling book value.

Illustration drawn for QuestionBuddy.

Understand Depreciation by the Straight Line and Written Down Value Methods

Factors. Cost (purchase price plus freight, installation and other costs of making it ready for use), estimated useful life and estimated scrap (residual) value.

SLM. Depreciation per year = (Cost − Scrap value) ÷ Useful life. Equivalent percentage on cost = depreciation ÷ cost × 100. The asset's book value falls by the same amount every year and reaches scrap value at the end of life.

WDV. Depreciation = Rate % × book value at the beginning of the year. Book value = Cost − accumulated depreciation. Because book value falls, depreciation is highest in the first year. The book value never reaches zero in theory.

Comparison. SLM: equal charge, simple; WDV: higher in early years when repairs are low and lower in later years when repairs are high, giving an even total burden on profit.

Part-year depreciation. Depreciation for the year = annual depreciation × months of use ÷ 12. The financial year is 1 April to 31 March. For WDV the first year is charged for months of use on the cost; from the next year the rate is applied to the full book value.

Costs to include. Freight, installation and trial run costs are part of cost. Repairs are an expense, not cost.

Typical question forms. (1) Compute for several years; (2) several machines bought at different dates; (3) find the rate from book values; (4) find original cost from book value after n years under WDV: Cost = Book value ÷ (1 − r)^n.

Depreciation by the Straight Line and Written Down Value Methods: key facts

SLM: Depreciation per year = (Cost minus Scrap) divided by Life
Equal every year
Book value falls to scrap value; Rate on cost = Depreciation / Cost.
WDV: Depreciation = Rate x Book value at the start of the year
Falls every year
Never reaches zero; Book value = Cost minus accumulated depreciation.
Part year: Annual depreciation x Months of use / 12; Financial year 1 April to 31 March.
Cost from book value (WDV): Cost = Book value / (1 minus rate) raised to n; n = number of full years.

How to answer Depreciation by the Straight Line and Written Down Value Methods questions

Choose the method, work out the cost, then calculate year by year; for part years adjust the first year.

1Cost = purchase price + freight + installation; exclude repairs.
2Find the months of use in the first year.
3SLM: annual depreciation from the formula; multiply by months/12.
4WDV: first year on cost for months of use; later years on the opening book value.
5Show a small table: year, opening value, depreciation, closing value.

Depreciation by the Straight Line and Written Down Value Methods in real life

The idea, met in an everyday situation. Answer the question in your own words, then compare with the model answer. The one-line hook is what to remember.

A delivery van

Suppose a bakery buys a van for ₹5,00,000 expecting to use it for 5 years and sell it for ₹50,000.

Find the yearly depreciation under SLM.

Try it first, then show the solutionSolution

Depreciable amount = 5,00,000 − 50,000 = ₹4,50,000.
Per year = 4,50,000 ÷ 5 = ₹90,000.

Answer: SLM depreciation ₹90,000 a year.

Memory hook: Cost minus scrap, shared over life.

Tricks to remember Depreciation by the Straight Line and Written Down Value Methods

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

SLM straight, WDV waning
SLM equal each year; WDV reducing each year.
Use it when: Pattern.
Months over twelve
Part-year depreciation uses months/12.
Use it when: First year.

Depreciation by the Straight Line and Written Down Value Methods: solved examples

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

Example 1: Which method? · 1 mark · MCQBoard level

Under which method is depreciation highest in the first year and falls thereafter?
(a) SLM
(b) WDV
(c) both equally
(d) neither

Try it first, then show the solutionSolution

Rate on declining book value.

Answer: (b) WDV

Example 2: SLM annual charge · 3 marks · Short answerBoard level

A machine costs ₹5,00,000, has a scrap value of ₹50,000 and a life of 5 years. Find the annual depreciation under SLM and the book value at the end of year 3. (3 marks)

Try it first, then show the solutionSolution

Annual depreciation = (5,00,000 − 50,000) ÷ 5 = ₹90,000.
Accumulated depreciation after 3 years = 2,70,000.
Book value = 5,00,000 − 2,70,000 = ₹2,30,000.

Answer: Depreciation ₹90,000; book value after 3 years ₹2,30,000.

Example 3: Part-year SLM and WDV · 5 marks · Short answerHarder board level

A machine was bought on 1 July 2024 for ₹6,00,000 and ₹40,000 was spent on installation. Find the depreciation for the year ended 31 March 2025 at 10% under SLM, and, separately, under WDV for the same year and the second year. (5 marks)

Try it first, then show the solutionSolution

Cost = 6,00,000 + 40,000 = ₹6,40,000.
SLM year 1: 6,40,000 × 10% × 9/12 = ₹48,000.
WDV year 1: the same, ₹48,000; book value 5,92,000.
WDV year 2: 10% × 5,92,000 = ₹59,200.

Answer: SLM ₹48,000; WDV year 1 ₹48,000; WDV year 2 ₹59,200.

Example 4: Three machines under WDV · 6 marks · Long answerHarder board level

Under WDV at 10% a firm has: Machine A bought 1 April 2022 for ₹2,00,000; Machine B bought 1 October 2022 for ₹1,20,000; Machine C bought 1 January 2024 for ₹80,000. The year ends on 31 March. Find the depreciation for the year ended 31 March 2025 and the book value of each machine on that date. (6 marks)

Try it first, then show the solutionSolution

A: 2022-23 20,000 (BV 1,80,000); 2023-24 18,000 (BV 1,62,000); 2024-25 16,200 (BV 1,45,800).
B: 2022-23 6 months = 6,000 (BV 1,14,000); 2023-24 11,400 (BV 1,02,600); 2024-25 10,260 (BV 92,340).
C: 2023-24 3 months = 2,000 (BV 78,000); 2024-25 7,800 (BV 70,200).
Depreciation for 2024-25 = 16,200 + 10,260 + 7,800 = ₹34,260; total book value = 1,45,800 + 92,340 + 70,200 = ₹3,08,340.

Answer: Depreciation ₹34,260; book values A 1,45,800, B 92,340, C 70,200.

Example 5: Back to the original cost · 4 marks · Short answerHOTS / competency

The book value of a machine at the end of the second year was ₹1,28,000 after depreciation at 20% under WDV, charged for full years. Find the original cost and the depreciation of each year. (4 marks)

Try it first, then show the solutionSolution

Book value = Cost × 0.8 × 0.8 = Cost × 0.64.
Cost = 1,28,000 ÷ 0.64 = ₹2,00,000.
Depreciation: year 1 = 40,000; year 2 = 20% of 1,60,000 = 32,000. Check: 2,00,000 − 72,000 = 1,28,000.

Answer: Cost ₹2,00,000; depreciation 40,000 and 32,000.

Where students lose marks in Depreciation by the Straight Line and Written Down Value Methods

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

Mistake: Subtracting scrap value under WDV
Using the SLM formula.
Wrong working
WDV depreciation on (cost − scrap).
Right working
WDV rate applies to book value (cost less accumulated depreciation); scrap is not subtracted.
Do this: Scrap enters only the SLM amount formula.
Usually costs: 1 mark
Mistake: Charging full-year depreciation on a part-year asset
Ignoring the date of purchase.
Wrong working
6,40,000 × 10% = 64,000.
Right working
6,40,000 × 10% × 9/12 = 48,000.
Do this: Count months from purchase to year end.
Usually costs: 1 mark
Mistake: Leaving installation out of cost
Treating it as an expense.
Wrong working
Cost = 6,00,000.
Right working
Cost = 6,00,000 + 40,000 = 6,40,000.
Do this: Costs of making the asset ready for use are capitalised.
Usually costs: 1 mark

Exam tips

Show a table with opening value, depreciation, closing value.
State clearly "rate applied on book value" for WDV.
Always add installation and freight to the cost.
For part years, show the months fraction.

Practice questions on Depreciation by the Straight Line and Written Down Value Methods

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
Under SLM, the depreciation charged every year is:
(a) different every year
(b) the same every year
(c) zero in the first year
(d) equal to the book value
Hint
Straight line.
Answer
(b) the same every year
Q2 · 4 marks · Short answerHarder board level
A machine cost ₹3,20,000 and was bought on 1 October 2023. Depreciation is charged at 15% WDV and the year ends on 31 March. Find the depreciation for 2023-24 and 2024-25 and the book value at 31 March 2025. (4 marks)
Hint
First year has 6 months.
Answer
2023-24: 3,20,000 × 15% × 6/12 = ₹24,000; BV 2,96,000. 2024-25: 15% × 2,96,000 = ₹44,400; BV ₹2,51,600.
Q3 · 3 marks · Short answerHarder board level
A firm buys a machine for ₹1,60,000 with freight ₹8,000 and installation ₹12,000. Estimated life 8 years; scrap ₹20,000. Find the annual SLM depreciation and the rate on cost. (3 marks)
Hint
Cost includes freight and installation.
Answer
Cost = 1,60,000 + 8,000 + 12,000 = ₹1,80,000. Annual depreciation = (1,80,000 − 20,000) ÷ 8 = ₹20,000. Rate = 20,000 ÷ 1,80,000 × 100 = 11.11%.
Q4 · 1 mark · Assertion-reasonHarder board level
Assertion (A): Under WDV the book value of an asset never becomes zero.
Reason (R): Depreciation is charged at a fixed rate on a reducing balance.
(a) Both A and R are true, and R is the correct explanation of A.
(b) Both A and R are true, but R is not the correct explanation of A.
(c) A is true, but R is false.
(d) A is false, but R is true.
Hint
Percentage of a shrinking number.
Answer
(a) Both A and R are true, and R is the correct explanation of A.
Q5 · 5 marks · Short answerHOTS / competency
An asset costing ₹4,00,000 is depreciated at 10% per year on WDV. Another identical asset is depreciated by SLM at 10% of cost. Find the depreciation of each asset in year 1 and year 3, and say in which year the two charges are equal. (5 marks)
Hint
WDV year 3 = 4,00,000 x 0.9 x 0.9 x 10%.
Answer
SLM: ₹40,000 every year. WDV: year 1 = 40,000; year 2 = 36,000; year 3 = 32,400. They are equal only in year 1; after that WDV depreciation is lower.

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.SLM formula?Show answer
(Cost − scrap) ÷ life.
2.WDV rate is applied to what?Show answer
The book value at the start of the year.
3.Part-year factor?Show answer
Months of use ÷ 12.
4.What is included in cost?Show answer
Purchase price, freight, installation.
5.Which method gives falling depreciation?Show answer
WDV.

Depreciation by the Straight Line and Written Down Value Methods: frequently asked questions

Is scrap value used in WDV?

Not in the rate calculation; the rate is applied to book value.

Is depreciation a cash expense?

No; it is a non-cash charge that spreads the cost.

When does the year start for part-year calculations?

On 1 April and ends on 31 March unless the question says otherwise.