PFE, Chapter 3: Capital budgeting 21
SIDEBAR: What is depreciation?
In computing the taxes they owe, Sally and Dave get to subtract expenses from their income. Taxes
are computed on the basis of the income before taxes (=income – expenses – depreciation – interest).
When Sally and Dave get the rent from their condo, this is income—money earned from their asset.
When Sally and Dave pay to fix the faucet in their condo, this is an expense—a cost of doing
business.
The cost of the condo is neither income nor an expense. It’s a capital investment—money paid for an
asset that will be used over many years. Tax rules specify that each year part of the capital
investments can be taken off the income (“expensed,” in the accounting jargon). This reduces the
taxes paid by the owners of the asset and takes account of the fact that the asset has a limited life.
There are many depreciation methods in use. The simplest method is straight-line depreciation. In
this method the asset’s annual depreciation is a percentage of its initial cost. In the case of Sally and
Dave, for example, we’ve specified that the asset is depreciated over 10 years. this results in annual
depreciation charges of
$100,000
- $10,000
10
initial asset cost
straight line depreciation= annually
depreciable life span
==
In some cases depreciation is taken on the asset cost minus its salvage value: If you think that the
asset will be worth $20,000 at the end of its life (this is the salvage value), then the annual straight-
line depreciation might be $8,000:
-
$100,000 $20, 000
$8, 000
10
straight line depreciation
initial asset cost salvage value
=
with salvage value
depreciable life span
annually
−
−
==
Accelerated depreciation
Although historically depreciation charges are related to the life span of the asset, in many cases this
connection has been lost. Under United States tax rules, for example, an asset classified as having a
5-year depreciable life (trucks, cars, and some computer equipment is in this category) will be
depreciated over 6 years (yes six) at 20%, 32%, 19.2%, 11.52%, 11.52%, 5.76% in each of the years
1, 2, … , 6. Notice that this method accelerates the depreciation charges—more than one-sixth of the
depreciation is taken annually in years 1-3 and less in later years. Since—as we show in the text—
depreciation ultimately saves taxes, this is in the interest of the asset’s owner, who now gets to take
more of the depreciation in the early years of the asset’s life.