What is straight line depreciation?

What is Straight Line Depreciation?

Straight-line depreciation is a method of allocating the cost of a tangible asset over its useful life in equal annual increments. This method assumes that the asset will lose value in a consistent manner from the time it is put into use until it reaches the end of its useful life or becomes obsolete. The formula to calculate straight-line depreciation is:

Annual Depreciation Expense = (Cost of the Asset - Salvage Value) / Useful Life of the Asset


  • Cost of the Asset includes the purchase price and any additional costs required to bring the asset into use.
  • Salvage Value is the estimated residual value of the asset at the end of its useful life.
  • Useful Life is the period over which the asset is expected to be used or the number of units of production expected from the asset.

Straight-line depreciation is widely used due to its simplicity and ease of calculation, providing a consistent expense allocation for each year of the asset's useful life.

How is straight line depreciation used in real estate?

In real estate, straight-line depreciation is used to allocate the cost of residential and commercial buildings (not the land) over their useful lives, as determined by tax regulations. The Internal Revenue Service (IRS) in the United States, for example, specifies a useful life of 27.5 years for residential properties and 39 years for commercial properties. This depreciation method allows real estate investors to reduce their taxable income by recognizing the expense of the property's wear and tear, deterioration, or obsolescence each year.

To apply straight-line depreciation in real estate, the cost of the property (excluding land, which is not depreciable) is divided by its useful life to determine the annual depreciation expense. This expense is then deducted from the property's income, lowering the taxable income and thereby reducing the tax liability of the investor.

For example, if an investor purchases a commercial building for $390,000 (excluding the cost of land) and the IRS's designated useful life for commercial property is 39 years, the annual straight-line depreciation expense would be $10,000 ($390,000 / 39 years). This amount can be deducted from the property's income on the investor's tax return, providing a tax benefit over the useful life of the property.

Straight-line depreciation is straightforward and predictable, making it a popular choice for real estate investors to manage their finances and tax liabilities effectively.

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