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What is the reducing balance method?

The reducing balance method of depreciation, also known as declining balance depreciation or diminishing balance depreciation, is a way of accounting for assets over a period of time. It is charged at a fixed rate, like the straight line method (also known as fixed instalment method or straight line depreciation). However, unlike the fixed instalment method, the percent rate is not calculated on the cost of an asset but on the book value of the asset, which in turn is calculated by subtracting depreciation from its cost. However, before we delve any further, it is important to look into the definition and cause of depreciation itself.

A recap: what is depreciation and what are its causes?

We all know that all fixed assets (illiquid and long-term purchases such as land or machinery) come with a price tag. Depreciation is something that consumes the value of that fixed asset with the passage of time. It is an expense of services consumed in the same way as other expenses occur like payment of wages, electricity, etc.

Depreciation lowers net profit as it is charged as an expense in the income statement. Net profit margin, also known as the ‘profit margin’ or ‘net profit margin ratio’ is the percentage of revenue remaining after you have factored in cost of goods sold, operating costs or expenses, taxes, interest, and preferred stock dividends, excluding common stock dividends. In other words, it is a ratio that shows the percentage of profit a company produces from its total revenue - or what percentage of your sales is actual profit.

For example, if a tractor cost £6,000 and it is assumed that it will be in service for three years, it means that one-third of its value is consumed at the end of the first year. Depreciation as such would be £2,000 i.e. one third of the cost of the tractor. Profit would be reduced by £2,000 and the value of the tractor in the balance sheet at the end of the first year would diminish from £6,000 to £4,000.

And what about the diesel consumed by the tractor? Diesel is consumed regularly, whereas the expense of the tractor is spread over many years.

What causes depreciation?

Economic factors, depletion, time and physical deterioration are the primary causes of depreciation. Each is briefly explained as following:

Physical deterioration

  • Wear and tear Taking the example of the tractor above, it is natural to expect that with the passage of time and usage, its parts (tyres, engine etc.) will eventually wear out. How long it remains in service depends upon its quality, maintenance and usage, among other things.
  • Erosion, Rust, Decay, etc. Land may suffer erosion by action of nature such as rain, wind, heat, etc. Similarly, the metals used in a motor vehicle will rust away.
  • Economic factors There is a possibility that the asset may be taken out of service even if it is in working condition.Obsolescence and inadequacy are two major factors that contribute towards this.
  • Obsolescence This is the process of becoming ‘out of date’. For example, there have been great technological advances in the field of computers. Both hardware and software undergo rapid upgrades, making a computer’s hardware - as well as software - obsolete, and much of it is taken out of service within two to three years. This, however, implies that they are not in working condition when they may still be in working order.
  • Inadequacy This happens when the asset is put out of service because of changes in the size of the business. For example, a small boat operated by a business at a coastal resort will no longer serve its purpose once the resort becomes popular and the numbers of tourists increase significantly. Under such circumstances, the resort owner may opt for a larger boat to ferry passengers. It does not mean that the smaller boat has become obsolete; it is just that it has become inadequate for the present business.
  • Time factor This is self-explanatory as erosion, decay, rust, wear and tear; along with obsolescence and inadequacy all happen with the passage of time. However, there are certain fixed assets which have a fixed life fixed in accounting terms. For example, you may lease a building for ten years and after ten years the amount you have paid for its lease becomes zero. Often the term ‘amortisation’ instead of ‘depreciation’ is used to denote depreciation of such assets.
  • Depletion Assets such as oil wells, mines, etc are of deteriorating usefulness, as raw material is extracted from them to make something else or they are sold in their raw state to other businesses.

The reducing balance method of depreciation results in declining depreciation expenses with each accounting period. In other words, it charges depreciation at a higher rate in the earlier years of an asset. The amount of depreciation reduces as the life of the asset progresses.

The reducing balance method of depreciation accurately gauges the depreciation, as it is usually seen that assets possess higher productive values during their initial years. For example, a new machine will have higher functionality when it is new and more likely to generate additional revenue for the company, and also requires less maintenance. The reducing balance method of depreciation ensures the depreciation expenses accurately display an asset’s functionality, productivity and its ability to generate revenue for the organisation.

Calculating depreciation using the reducing balance method

To calculate reducing balance depreciation, you need to have knowledge of the following:

  • Asset cost This refers to the asset's net value at the start of an accounting period, plus any additional cost incurred to make that asset ready for use. It is calculated by deducting the accumulated (total) depreciation from the cost of the fixed asset. ‘Net book value’ is the asset's net value at the start of an accounting period.
  • Residual value Also known as scrap or salvage value, this refers to the value of the asset at the end of its life.
  • Depreciation factor This correlates to a percentage how much the asset will depreciate with each passing year. For example, ‘1’ is 100%, ‘0.5’ is 50%.Depreciation under the reducing balance method may be calculated as follows:

Depreciation per annum = (net book value - residual value) x depreciation factor (rate %).

Subtract the depreciation charge from the current book value to calculate the remaining book value.

The above mentioned two steps are to be repeated every year till the asset is in use. In the final year for which the asset will be used, you should subtract the residual value from the current book value - the resulting amount should be treated as an expense.

For example, a company buys a van for £5,000. It is estimated that the van is likely to lose 40% of its value each year, and the scrap value will be £1,000. Calculate the first five years of depreciation using the reducing balance method calculation.

Using the formula:

Depreciation per annum = (net book Value - residual value) x depreciation factor (rate %)

Example 1 -

An asset’s useful life is determined to be three years.

Cost of the asset is £2,000.

Residual value is £500.

Rate of depreciation is 50%.

How will you calculate the depreciation expense for these three years?

NBV RV Rate Depreciation Accumulated depreciation
Year 1: (2000 - 500) x 50% = 750 750
Year 2: (1250 - 500) x 50% = 375 1125
Year 3: (875 - 500) x 50% = 375* 1500

As is evident from the above example, the depreciation expense under the reducing balance method gradually reduces over the asset’s useful life. In the case of the fixed instalment method, the amount of annual depreciation remains the same - whereas in the case of the reducing balance method the amount of annual depreciation progressively declines.

The reducing balance method of depreciation is most appropriate in cases of assets that offer higher productivity during their initial years. Computers, for example, have better functionality during their initial years of being in service.Also, advancing technology makes computersrapidly obsolete.

Using the reducing balance method to calculate depreciation of a computer ensures that higher depreciation is charged in initial years of its operation. Under this method the real cost of using an asset is the sum total of depreciation and the repair cost associated with the equipment or the machinery. This is a more reliable method, as in initial years the high rate of depreciation and low maintenance cost balance each other out.

With the progress of time, as an asset gets older, the depreciation rate lowers but the maintenance cost goes up and, as such, the combined effect of both these costs remain almost constant on the profit and loss statement for each year. A major shortcoming of this method is that it takes a very long time to determine the residual value, or scrap value of an asset.

The time period can be shortened, but then the depreciation rate would have to be much higher, which can put excess burden during the initial years. This method is often used by income tax authorities for granting depreciation allowances.

Calculating the depreciation rate

Correctly calculating depreciation is of paramount importance when it comes to the reducing balance method. Please use the formula given below to calculate the depreciation rate.

When the cost of asset, residual value and useful life of an asset is given:

r = 1 - (S/C)1/n


r = Rate of depreciation

n = Estimated useful life of asset

S = Residual value after the expiry of useful life

C = Original cost of asset

Example 2:

If n = 3 years, S = £64,000 and C = £1,000,000 calculate rate of depreciation.

r = 1 - (64,000/1,000,000)1/3

= 1 - 40/100

= 60/100

= 60%

Key differences between the straight line method and reducing balance method

Key differences between straight line method and reducing balance method are:

Straight line method

  • The rate of depreciation and the amount remain constant.
  • The cost of assets each year form the basis of determining depreciation percentage.
  • The value of an asset at the end of its life is zero.
  • As the asset ages, the cost of its repair goes up. But as mentioned earlier, the depreciation amount remains unchanged. This diminishes annual profit.
  • Computation of depreciation under thestraight line method is relatively easy and straightforward.

Reducing balance method

  • The rate of depreciation remains unchanged, but the amount gradually decreases.
  • The book value of assets forms the basis of determining depreciation percentage.
  • The value of an asset at the end of its life is never zero.
  • As the asset ages, the cost of its repair goes up, but so does the depreciation amount. They balance each other out, so there is little or no effect on annual profit/loss.
  • Computation of depreciation under reducing balancing method is always possible, but it comes with its own share of complexities.
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