Depreciation Period Change

rpindoria

How does one make an adjustment in a period ( P12 this year say) to reflect a change ( shortening) of depreciation period.This may included assets which in the Year in question have a nil NBV due to the shorter period.Obviously the adjustment can not be made in previous years as the change in ploicy occured in say this year from say 5 yr to 10 yrs on the assets concerned
I see I can alter the period in the FA card, but how can I run the depreciation caculation which in effect is to create a negative adjustment in P12 for the excessive depreciation in previous periods