1Why assets are depreciated
A company buys a delivery van for €20 000. It will use the van for 5 years and then sell it for about €2000.
Charging the full €20 000 as a cost in the year of purchase would make that year look terrible and the next four look too good. The van helps earn revenue in all five years.
Depreciation spreads the cost of an asset over its useful life. Each year a part of the cost appears as an expense, the depreciation charge D.
Four terms come back in every question:
- Cost: the price paid for the asset.
- Salvage value (or residual value): what the asset is expected to be worth at the end of its life.
- Useful life n: the number of years the asset will be used.
- Book value BV: cost minus all depreciation so far (the accumulated depreciation). It is the value shown on the balance sheet.
Only cost − salvage is used up, so that is the total amount to depreciate. Here that is €18 000.
Self-check A machine cost €10 000. So far €3000 of depreciation has been charged. What is its book value?
- €10 000
- €13 000
- €3000
- €7000
Answer: €7000. Book value = cost − accumulated depreciation = 10 000 − 3000 = €7000. Adding the depreciation (€13 000) goes the wrong way: an asset loses value as it is used.
2Straight-line depreciation
The simplest method charges the same amount every year:
D = (cost − salvage) / n
For the van: D = (20 000 − 2000) / 5 = €3600 per year.
After k years the book value is:
BVk = cost − k · D
After 3 years: BV = 20 000 − 3 · 3600 = €9200. After 5 years the book value equals the salvage value, €2000.
Self-check An asset costs €10 000, has a salvage value of €2000 and a life of 4 years. What is the straight-line depreciation per year?
- €2000
- €2500
- €3000
- €8000
Answer: €2000. (10 000 − 2000) / 4 = 8000 / 4 = €2000. €2500 forgets to subtract the salvage value, €3000 adds it, and €8000 is the total over all four years.
3Accelerated methods
Many assets lose most of their value early. Accelerated methods charge more in the first years and less later.
Double-declining balance (DDB) uses a fixed rate of 2/n on the book value at the start of each year:
D = (2/n) · BVstart of year
The salvage value is not subtracted first. It only acts as a floor: the book value never goes below it.
Sum of the years’ digits (SYD) depreciates cost − salvage with a fraction that counts down. For a life of n years, add the digits 1 + 2 + … + n:
SYD = n(n + 1)/2
Dk = (cost − salvage) · (n − k + 1) / SYD
For the van, SYD = 5 · 6 / 2 = 15. Year 1 uses 5/15, year 2 uses 4/15, and so on: €6000, €4800, €3600, €2400, €1200.
The figure shows the van’s book value. The dashed line is straight-line: an even fall. The solid line is DDB: a steep fall at first that flattens out. Both end at the salvage value.
Self-check An asset has a useful life of 5 years. What is the yearly rate for double-declining balance?
- 10%
- 20%
- 40%
- 50%
Answer: 40%. The straight-line rate is 1/5 = 20%, and DDB doubles it: 2/5 = 40%. 20% is the straight-line rate, not the doubled one.
5A worked example
Follow every step. Try to predict the next one before you open it.
Worked exampleA delivery van costs €20 000, has a useful life of 5 years and a salvage value of €2000. Using the double-declining-balance method, find the depreciation charge D in year 3.
1rate = 2/n = 2/5 = 0.4
The salvage value is not subtracted: DDB works on the full book value.
2The book value at the start is the cost, €20 000.
D1 = 0.4 · 20 000 = 8000
BV = 20 000 − 8000 = 12 000
3D2 = 0.4 · 12 000 = 4800
BV = 12 000 − 4800 = 7200
4D3 = 0.4 · 7200 = 2880
The book value becomes 7200 − 2880 = €4320.
5€4320 is still above the salvage value of €2000, so the full charge is allowed. The charges fall each year (8000, 4800, 2880), as DDB should.
Answer D = €2880 in year 3.
7How exam questions look
- Easy: straight-line. Find the yearly depreciation, or the book value after a number of years.
- Medium: double-declining balance. Find the charge in a given year, working through the book value year by year.
- Hard: sum of the years’ digits. Find SYD, then the fraction for the year asked.
Write a small table with the year, the book value at the start, the charge and the book value at the end. It prevents most mistakes.