Depreciation is dependent on a number of estimates. When a change in an estimate is required, the change is made: Options in the current year. in the future year. to prior periods. Both a and b above.
The answer would be : Both A and B above When we change the estimation method of depreciation , we should change the depreciation calculation that we made in the past before we impose the new method, so we not underestimate or overestimate the Assets