Hi Barthelemy,
As per Accounting Standard, if impairment is happened then the depreciation for the future periods will be based on the revalued figure. So if you do unplanned depreciation the gross block will not change and thereby future depreciation will be wrong.
For example Asset value is 100000 useful life 10 years, after two years Depreciable value is 80000 and now imapirment is happened and the revalue is 40000, impairment loss for current year is 40000 and depreciation for the balance 8 years is 5000. If you post unplanned depreciation for 40000 it takes care of current year requirement but depreciation for the next year will be 10000 which is wrong.
Hope it helps for Justin.
