Tibble Corporation recently determined that the recoverable value of one of its milling machines is less than its current carrying amount. In addition, the machine's useful life is now expected to be three years less than what the company had originally estimated. Explain how the impairment loss and the reduction in useful life will affect the company's annual depreciation expense calculation and the accumulated depreciation account balance for

(a) Previous years,

(b) The current year,

(c) Future years.