Depreciation

Depreciation has related but distinct meanings in economics and accounting. Economic depreciation is the decline in an asset’s value associated with aging, wear, and obsolescence. Accounting depreciation is the systematic allocation of an asset’s depreciable amount over its useful life; it is not necessarily a measurement of changes in its market price. The distinction matters because financial reporting, taxation, and national economic statistics can assign different depreciation amounts to the same asset. (ifrs.org)

Accounting purpose and scope

Long-lived tangible assets—such as machinery, vehicles, and buildings—provide benefits over several accounting periods. Rather than treating their entire recognized cost as an immediate expense, depreciation allocates the depreciable amount across the periods in which those benefits are consumed. A period’s charge may be recognized as an expense or included in the cost of another asset, such as goods manufactured using the equipment. (openstax.org)

Land and buildings are normally accounted for separately. Under International Accounting Standard 16 (IAS 16), land generally has an unlimited useful life and is not depreciated, whereas buildings ordinarily are depreciable. Exceptions include land with a limited useful life, such as certain quarry or landfill sites. Significant components of a larger asset may also require separate depreciation; an aircraft’s engines and airframe are an example. (ifrs.org)

Measurement and estimates

The principal inputs are:

Recognized cost or substituted amount: the amount assigned to the asset under the applicable accounting basis.
Residual value: the estimated net disposal proceeds, assuming the asset were already at the age and condition expected at the end of its useful life.
Useful life: the period for which the entity expects to use the asset, or the production units it expects to obtain.
Depreciation method: the pattern used to allocate the depreciable amount. (ifrs.org)

In a simple cost-based calculation,

\text{Depreciable amount}=\text{Cost}-\text{Residual value}.

Useful life need not equal physical lifespan: an entity may replace an asset before it becomes unusable. IAS 16 requires useful life, residual value, and the depreciation method to be reviewed at least annually. Revisions reflect changed estimates of remaining benefits, rather than automatically implying that earlier calculations were erroneous. (ifrs.org)

Under IAS 16, depreciation begins when the asset is available for its intended use. Temporary idleness does not ordinarily stop depreciation, although a usage-based method can produce no charge when there is no production. Repairs and maintenance do not, by themselves, eliminate the need to depreciate an asset. (ifrs.org)

Principal methods

Common methods include straight-line, units-of-production, and declining-balance depreciation. They differ in the timing of charges, not necessarily in the total depreciable amount allocated. (openstax.org)

Straight-line depreciation allocates equal amounts over the estimated useful life:

D=\frac{C-R}{n},

where $C$ is cost, $R$ residual value, and $n$ useful life in years.

Units-of-production depreciation allocates cost according to measured use:

D_t=(C-R)\frac{q_t}{Q},

where $q_t$ is the period’s output or usage and $Q$ is estimated lifetime output or usage.

Declining-balance depreciation applies a fixed rate to the opening carrying amount. Under the double-declining-balance method,

D_t=\frac{2}{n}B_{t-1},

where $B_{t-1}$ is opening book value. Charges are larger initially and smaller later; they must not reduce book value below the estimated residual value. (openstax.org)

For a hypothetical machine costing $100,000, with a $10,000 residual value and a five-year useful life, straight-line depreciation is $18,000 annually. After two full years, accumulated depreciation is $36,000 and book value is $64,000, assuming no other adjustments. Double-declining-balance depreciation would instead charge $40,000 in the first year and $24,000 in the second.

Financial-statement effects

Accumulated depreciation records depreciation recognized to date in a contra-asset account. In the simplest historical-cost case, an asset’s net amount on the balance sheet equals its original cost less accumulated depreciation. This book value should not be confused with a current resale valuation. (openstax.org)

Depreciation is a noncash expense: recording a charge does not itself involve a contemporaneous cash payment. Under the indirect method of preparing a cash-flow statement, depreciation deducted in arriving at net income is added back when reconciling income to operating cash flow. This adjustment does not mean that depreciation creates cash or establishes a replacement fund. (openstax.org)

Depreciation also differs from impairment. Depreciation systematically allocates an amount over time; impairment addresses a carrying amount that exceeds the asset’s recoverable amount. Under IAS 36, an impairment loss reduces carrying amount, and subsequent depreciation is adjusted to allocate the revised amount over the remaining useful life. (ifrs.org)

Tax depreciation

For taxation, depreciation is a deduction through which the cost or other tax basis of eligible property is recovered. Tax rules may prescribe methods, recovery periods, and conventions different from those used in financial reporting. Consequently, tax depreciation is not necessarily an estimate of actual economic deterioration. (irs.gov)

In the United States, most eligible property is depreciated under the Modified Accelerated Cost Recovery System (MACRS). It includes specified declining-balance and straight-line methods. Separate provisions permit accelerated allowances or immediate deductions for qualifying expenditure, subject to statutory conditions; these are tax treatments rather than measurements of physical wear. (irs.gov)

Economic depreciation and national accounts

In national accounts, consumption of fixed capital measures the using up of fixed assets through aging, wear, and obsolescence. The U.S. Bureau of Economic Analysis distinguishes historical-cost valuation from current-cost valuation, which measures depreciation using prices of the relevant current period. This differs from simply adopting businesses’ tax deductions. (bea.gov)

The distinction between gross and net economic measures depends on depreciation. Gross domestic product includes consumption of fixed capital; net domestic product subtracts it:

\text{NDP}=\text{GDP}-\text{Consumption of fixed capital}.

Investment replenishes or increases the fixed-asset stock, while depreciation reduces it. (bea.gov)

Economic depreciation is difficult to observe directly for many assets. Statistical estimates therefore use assumptions about depreciation patterns and the survival of earlier investment. BEA uses the perpetual inventory method and geometric depreciation for most asset types, leaving a progressively smaller share of an original investment in the net stock over time. (bea.gov)

Interpretation and limitations

Accounting depreciation depends on estimates, not direct observation of a unique annual loss in value. Different useful lives, residual values, or allocation methods can change reported charges. Moreover, an asset can remain depreciable even when its fair value exceeds its carrying amount: accounting allocation and market valuation answer different questions. These limitations make the measurement basis and underlying estimates essential to interpreting a depreciation figure. (ifrs.org)