Corporations Reap Billions in Tax Breaks Under Bonus Depreciation Under this method, the total depreciable amount is divided by the estimated total units the asset will produce over its useful life. Depreciation expense is then calculated based on the actual units produced in a given period. For example, if a machine is expected to produce 100,000 units over its life and costs $100,000, the depreciation expense per unit would be $1. If the machine produces…