Which depreciation method is best suited for an asset whose wear and tear relates closely to its usage?

The units-of-production method is best suited for an asset whose wear and tear relates closely to its usage because it allocates depreciation based on the actual usage or output of the asset rather than simply time. This method ties the expense directly to the asset's operational activity; as the asset is used more, it absorbs more depreciation expense.

For example, if a piece of machinery is used heavily in one year and much less in another, the units-of-production method will reflect this variability, providing a more accurate representation of the asset's economic value and the expense related to its use. In contrast, the straight-line method allocates the same amount of expense each period regardless of actual usage, which may not accurately reflect the wear and tear that the asset experiences.

The half-year convention and modified half-year convention are often used for tax purposes to simplify depreciation calculations, especially for assets that are not tied as directly to usage. These methods do not consider the actual operation or wear of the asset in relation to its output. Thus, for assets where wear and tear are closely linked to how much they are used, the units-of-production method is clearly the most appropriate choice.