The way depreciation works is that a company buys something, like a computer, which is a business expense. Then at the end of the year, you're out the $2000 tha

The way depreciation works is that a company buys something, like a computer, which is a business expense. Then at the end of the year, you're out the $2000 that you paid, but you still have the computer, which is now a used device and is now a year older. So it's no longer worth $2000 but it's not worth nothing. Suppose it loses $500 in value. Then the book value of the asset becomes $1500 and you have depreciation expense of $500. That depreciation is the deduction for this year, they don't let you deduct the whole $2000 the year you bought it. Next year you can deduct some more, until the book value of the asset is scrap or you dispose of it or sell it. Estimating how much value it lost is subjective so the government specifies what percent of the value you can deduct each year. Straight line deprecation is when the depreciation expense is the same percentage of the original cost every year. Accelerated depreciation is when the early years use a higher percentage than the later years. In both cases the total amount of depreciation is the same but accelerated depreciation is often a better approximation for actual value. The true market value of a piece of equipment will decline more in absolute dollars in the first year than the fourth year. It's also what businesses typically pick when given the choice, because a bigger deduction now is better than a bigger deduction later. It's not any kind of tax dodge at all, it's just an accounting method in the tax code.