Depreciation is a core accounting idea because many non-current assets lose usefulness over time. Businesses must recognize this loss so profit and asset values are reported more fairly.

What depreciation means

A business buys many non-current assets to help earn revenue over several accounting periods. These assets are not normally used up immediately, but their ability to generate future benefits usually decreases as they are used or as time passes.

This means depreciation is an expense for the period, not a sudden write-off of the whole cost when the asset is purchased.

Adjusting entry for depreciation (Dr Depreciation Expense, Cr Accumulated Depreciation) alongside T-accounts showing the resulting debit balance for the expense and credit balance for the contra-asset. This visual reinforces how depreciation reduces profit for the period while accumulated depreciation reduces the asset’s carrying amount on the statement of financial position (without changing the asset’s original cost figure). Source

It is also not simply a measure of market price changes. In accounting, the focus is on how much of the asset’s service potential has been used up during the period.

Main causes of depreciation

Depreciation happens because most non-current assets do not last forever. Their value to the business falls as their economic usefulness is gradually consumed.

Physical deterioration

Many assets depreciate because of wear and tear. Machinery, motor vehicles, fixtures, and equipment become less efficient or less reliable after repeated use. Parts may wear out, performance may decline, and repair costs may rise.

Physical deterioration may be caused by:

• continuous use in production

• heavy workloads or long operating hours

• exposure to weather, rust, damp, or damage

• poor maintenance

Even when an asset is maintained carefully, use over time usually reduces its remaining useful life.

Passage of time

Some assets lose value mainly because time passes, even if they are not heavily used. A lease, patent, or license may have a fixed legal life. As the end of that period gets closer, the future benefit available to the business becomes smaller.

This shows that depreciation is not always linked only to physical damage. An asset can decline in usefulness simply because the period during which it can legally or economically benefit the business is getting shorter.

Obsolescence

An asset may also depreciate because it becomes obsolete. This means it is no longer as useful as before because something better or more suitable is available. Obsolescence can happen quickly, especially where technology changes rapidly.

Common causes of obsolescence include:

• new and more efficient machinery becoming available

• changes in customer preferences

• changes in production methods

• new legal or safety requirements

An asset may still function, but if it no longer meets the needs of the business efficiently, its economic value has fallen.

Why businesses account for depreciation

The purpose of accounting for depreciation is to ensure that financial statements present a more reliable view of profit and asset values. It helps match the cost of using a non-current asset to the periods that benefit from that use.

Matching and accruals

The matching and accruals concepts are central to depreciation. If a machine helps produce goods over several years, its cost should not be charged entirely to the first year. Instead, part of that cost should be treated as an expense in each accounting period that benefits from the machine’s use.

Without depreciation:

• profit in the year of purchase would be understated if the full cost were charged immediately, or

• profit in later years would be overstated if no asset cost were charged at all

Depreciation therefore helps each period bear a fair share of the asset’s cost.

Prudence

The concept of prudence supports depreciation because assets and profits should not be overstated. If depreciation is ignored, the carrying amount of a non-current asset may remain too high in the statement of financial position, even though some of its usefulness has already been consumed.

At the same time, profit for the period would also be overstated because no expense would have been recognized for the asset’s use. Charging depreciation reduces this risk and gives users of accounts more cautious and realistic information.

Historic cost and going concern

The historic cost concept is also relevant. Non-current assets are initially recorded at cost, and depreciation then allocates that cost over the asset’s useful life. This keeps accounting records based on a clear and objective starting point.

The going concern concept matters because a business is assumed to continue operating. Since the asset is expected to help earn revenue over future periods, its cost is spread over those periods rather than treated as a short-term item. Depreciation reflects the continuing use of the asset in the business.

Important points for exam answers

When explaining depreciation, it is important to focus on loss of usefulness to the business, not just falling resale price.

You should also remember:

• depreciation is charged on assets with a limited useful life

• it is an expense in the statement of profit or loss

• it reduces the carrying amount of the asset in the statement of financial position

• it helps avoid overstating both profit and assets

• it does not mean cash is being set aside automatically to replace the asset

A strong answer links the causes of depreciation to the purpose of charging it and refers clearly to relevant accounting concepts.