Depreciation

Depreciation is the accounting practice of spreading the cost of a long-lived asset (buildings, equipment, vehicles) across the periods it benefits. Under accrual-accounting, a company that buys a $10 million machine does not write off the entire cost in year one. Instead, it estimates the machine’s useful life (say, 10 years) and recognizes $1 million of depreciation expense each year. Depreciation is a non-cash charge: no cash leaves the company when the expense is recorded. But it significantly reduces reported profit. The most common methods are straight-line-depreciation (equal amounts each year) and declining-balance-depreciation (larger amounts early).

Why depreciation exists

Assets like buildings and equipment benefit the company over multiple years. Under the matching principle of accrual-accounting, the cost must be matched to the periods it benefits. If a company bought a $10 million factory with a 20-year life, it would be misleading to expense $10 million in year one (profit would crash) and then report zero depreciation for 20 years.

Depreciation solves this by spreading the cost. The income statement is more accurate, and profits are reported consistently across years.

Components of depreciation calculation

To calculate depreciation, three things must be estimated:

1. Asset cost — what the company paid for the asset, including installation and other capitalized costs.
2. Useful life — how many years (or units) the company expects to use the asset. This is an estimate based on industry experience and the company’s own circumstances.
3. Salvage value — what the company expects to recover when it disposes of the asset (often zero or nominal).

Depreciation = (Asset cost - Salvage value) ÷ Useful life

For example: A truck costs $50,000 with an estimated 10-year life and $5,000 salvage value. Under straight-line method, annual depreciation is ($50,000 - $5,000) ÷ 10 = $4,500.

Depreciation methods

Companies can choose from several depreciation methods, each spreading the cost differently:

• Straight-line-depreciation — equal expense each year. Simplest and most common.
• Declining-balance-depreciation — larger expense early, smaller later. Reflects that assets lose value faster early.
• Units-of-production-depreciation — expense is tied to actual use. A truck is depreciated per mile driven.

The choice of method is a company accounting policy, disclosed in footnotes and must be consistent year-to-year.

Accumulated depreciation and book value

Accumulated depreciation is the total depreciation expense to date. On the balance sheet:

• Asset at cost: $10,000,000
• Accumulated depreciation: ($4,000,000)
• Net book value: $6,000,000

Net book value is not market value; it is the undepreciated cost. A building might be worth far more (or less) than its net book value.

Depreciation and cash flow

A key insight: depreciation is a non-cash expense. The company recorded the cash outflow when it bought the asset. Each year’s depreciation expense reduces profit but not cash.

This is why the cash flow statement adds back depreciation to net income: it was subtracted in calculating earnings but didn’t cost cash.

A company with large depreciation can have strong cash flow despite low reported earnings. This is why investors look at cash flow in addition to earnings.

Depreciation policy choices and earnings management

The useful life estimate directly affects depreciation expense. A company using a 20-year life recognizes lower annual depreciation (and higher profit) than one using a 10-year life for the same asset.

This is a gray area in earnings-management. A company wanting to boost reported earnings can use optimistic (long) useful lives; a conservative company can use shorter lives. Within GAAP, both are acceptable. The choice must be disclosed and reasoned, but the impact on earnings is real.

Tax depreciation vs. book depreciation

For tax purposes, companies use MACRS (Modified Accelerated Cost Recovery System), which typically depreciates assets faster than book depreciation. This creates a difference: the company might record $10 million of book depreciation but $12 million of tax depreciation. This difference is a key driver of deferred-tax-liability and deferred-tax-asset.

See also