If a Company registered before Companies Act, 2013 comes into force and following the WDV method for calculating Depreciation. However with effect from 1st April 2015 the company wants to change the method from WDV to SLM Method. As we know that it is a retrospective change so Company has to change the same from inception. Now what SLM rates to follow i.e. specified depreciation rate as per Companies Act, 1956 or Useful life as per Companies Act, 2013.