Consider that you are purchasing an asset that you can either declare as an expense immediately in the first year for its full value or you can depreciate with 3-year MACRS (depreciation rates: 33.33%, 44.45%, 14.81%, and 7.41%). The tax rate will not be affected by the purchase. The after tax MARR is 10%. Then, from a purely financial standpoint, based on the NPV of the annual tax savings, what is preferable: to deduct immediately or to depreciate it with MACRS? Or are they the same of does it depend on tax rate