Depreciation Depletion and Amortization

The terms depreciation depletion and amortization are often used to mean the same thing, the reduction in the value of an asset. Most assets have a limited life and therefore reduce in value over time. An estimate of this reduction in value is charged as an expense to the income statement each accounting period.

To be more specific about the terms depreciation depletion and amortization, we will look at an example of each.


Depreciation refers to the wear and tear of a physical asset due to it being used, and is therefore applied to tangible assets.

For example, if a machine is purchased for 12,000 and is expected to have a useful life of 5 years, and a salvage value of 2,000, then the straight line depreciation expense is given by the formula.

Depreciation expense = (Cost – Salvage value) / Useful life

The depreciation expense calculation is as follows.

Depreciation expense = (Cost - Salvage value) / Useful life
Depreciation expense = (12,000 - 2,000) / 5 = 2,000 a year

The machine is expected to reduce in value due to being used over the five year period. The cost to the business of this wear and tear is 2,000 a year.

Depreciation expense
Account Debit Credit
Depreciation expense 2,000
Accumulated depreciation 2,000
Total 2,000 2,000


Depletion means to exhaust the supply of a resource. In this case the asset is the cost of extracting the resource which needs to be depleted as the resource is extracted. There is no wear and tear, the natural resource is simply being used.

For example, if a business is mining for a coal, and has expenditure of 1,500,000 on purchasing, exploring, and developing the coal mine, this expenditure is an asset of the business which will reduce in value as the coal is extracted.

The expenditure on the mine is therefore the cost of getting the coal and is depleted as the coal is extracted. When all the coal has been extracted the asset will have zero value.

Now if the amount of coal in the mine is expected to be 200,000 units, then the depletion expense is given by the formula:

Depletion expense = Cost / Expected units over lifetime

The depletion expense calculation is as follows.

Depletion expense = Cost / Expected units over lifetime
Depletion expense = 1,500,000 / 200,000 = 7.50 per unit

So if in an accounting period 10,000 units are extracted, the depletion expense would be 10,000 x 7.50 = 75,000.

Depletion expense
Account Debit Credit
Depletion expense 75,000
Accumulated depletion 75,000
Total 75,000 75,000


Amortization quite literally means to ‘bring to death, and is the gradual extinction of an intangible asset or liability by periodic amounts. In this case there is no physical substance to the asset or liability, there is nothing to wear and tear over time, so the term depreciation is not applicable.

For example, an intangible asset such as a patent might have cost 40,000 and have a ten years of its useful life remaining. The amortization expense is given by the formula:

Amortization expense = Cost / Expected useful life

The amortization expense calculation is as follows.

Amortization expense = Cost / Expected useful life
Amortization expense = 40,000 / 10 = 4,000 a year
Amortization expense
Account Debit Credit
Amortization expense 4,000
Accumulated amortization 4,000
Total 4,000 4,000

An item which sometimes causes confusion is that leasehold improvements are said to be amortized not depreciated. The reason for this is that the physical assets resulting from the improvements belong to the landlord not the tenant. What the tenant has done is improve the value of an intangible asset, the leasehold, so the improvements are amortized over the remaining lease term.

In the case of a liability, a loan of 20,000 might be repaid in 10 installments of 2,000 per year.

Loan amortization
Account Debit Credit
Loan 2,000
Cash 2,000
Total 2,000 2,000

The value of the loan on the balance sheet reduces over time, and the loan is said to be amortized over the ten year period.

Last modified April 30th, 2019 by Michael Brown

About the Author

Chartered accountant Michael Brown is the founder and CEO of Double Entry Bookkeeping. He has worked as an accountant and consultant for more than 25 years in all types of industries. He has been the CFO or controller of both small and medium sized companies and has run small businesses of his own. He has been a manager and an auditor with Deloitte, a big 4 accountancy firm, and holds a BSc from Loughborough University.

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