Understanding Depreciation

What is depreciation? Depreciation is the accounting process of allocating a tangible asset’s cost over its useful life. Essentially, the concept represents how much of an asset’s value has been used over time, considering wear and tear, obsolescence, or age. When a company buys expensive assets such as equipment or vehicles, these assets do not account for the entire cost in the first year. Depreciation spreads these costs over the asset’s useful life.

Accumulated Depreciation, Carrying Value, and Salvage Value

Accumulated depreciation represents the total depreciation a company has recorded for an asset over time. This separate account pairs with the asset account, effectively lowering the asset’s overall value on the company’s books. The carrying value or book value is what’s left of the asset’s original cost after subtracting all the accumulated depreciation. Lastly, the salvage value is the estimated cash a company expects to get back once it’s time to say goodbye to the asset after taking all depreciation charges.

Types of Depreciation

There are several methods to allocate depreciation over the useful life of capital assets.


The straight-line method evenly distributes the depreciation expense over the asset’s useful life. This method ensures that each year carries an identical charge for the depreciation expense until the asset reaches its residual value. The straight-line formula is:

  • (Cost of asset – salvage value) / useful life

For instance, a company purchases a machine for $100,000 with an expected useful life of ten years and a salvage value of $10,000. The annual depreciation expense calculation using the straight-line depreciation method would be:

  • (100,000 – 10,000) / 10 = $9,000

Declining Balance

The declining balance calculates depreciation from the asset’s carrying value, not its final salvage value. Since an asset’s carrying value is higher before any depreciation happens, using a consistent percentage to calculate depreciation means the amount is larger at the start and gets smaller over time.

  • Book value of the asset (1/useful life)

For example, a company purchases equipment for $50,000 and has a useful life of five years. The formula will look like this:

  • 50,000 (1/5) = $10,000

The asset will lose $10,000 in value each year. The calculations would continue as follows:

  • Year one: (50,000 – 10,000) = $40,000
  • Year two: (50,000 – 10,000) x (1/5) = $8,000
  • Year three: (50,000 – 10,000 – 8,000) x (1/5) = $6,400

Double-Declining Balance (DDB)

The double-declining balance method effectively doubles the depreciation rate of the declining balance method. This approach front-loads the depreciation expense, acknowledging that some assets lose value more quickly during their initial years of use.

The DDB method intensifies the depreciation expense in the earlier years of an asset’s life by applying the formula DDB = Current Book Value x (2/useful life).

Let’s take the same example as above, where a company purchases equipment for $50,000 with a useful life of five years. The DDB calculation would look like this:

  • Year one: (50,000 x (2/5) = $20,000
  • Year two: (50,000 – 20,000) x (2/5) = $12,000
  • Year three: (50,000 – 20,000 – 12,000) x (2/5) = $7,200

Sum-of-the-Years’ Digits (SYD)

The sum-of-the-years’ digits (SYD) method promotes a higher expense rate in the earlier years. Calculate by adding the digits of the asset’s useful life. For instance, an asset with a useful life of five years would accumulate a sum base by adding digits from one to five, equating to 1 + 2 + 3 + 4 + 5 = 15.

In the initial year, depreciation accounts for 5/15 of the asset’s depreciable base. The following year, it shifts to 4/15, continuing this decremental pattern through the fifth year, where the final 1/15 of the base is depreciated. Here, the “depreciable base” refers to the asset’s cost minus any estimated salvage value.

Units of Production

The units of production method evenly distributes the depreciation cost per unit produced, making it particularly effective for assets whose worth is directly tied to their output or usage volume rather than their time-based service life. This approach calculates the depreciation expense by applying a cost-per-unit depreciation rate to the total quantity of units produced during the financial period.

Choosing the most appropriate depreciation method for your assets will depend on various factors, such as the asset’s intended use, useful life, and expected pattern of decline in value. Consult an accountant or financial advisor to identify the best approach for your specific situation. 

In Summary

Understanding depreciation is crucial for businesses and investors because it impacts financial statements, tax liabilities, and investment decisions. By spreading the cost of a tangible asset over its useful life, you can allocate expenses more accurately, influencing profitability and financial health. Always keep in mind that while depreciation may seem complex, it is ultimately a valuable tool for managing assets and maintaining accurate financial records.

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