If an there is change in method of depreciation from SLN method to WDV method, how do you treat the difference of depreciation ?

When there is a change in method of depreciation then revised depreciation shall be calculated from retrospectively and any difference shall be charged i.e Debited/Credited to profit & loss Account..

Change in depreciation method is change in accounting estimates as per IAS8. For example if you are depreciated asset of value100,000/- on SLN and estimated useful life of asset is 5 years. in the start of3rd year management decided to change the method to WDV. Carrying value of assets60,000 after two years SLN Dep. on this CV you have to charge the WDV % and the effect only is prospective.