Formalities at custom port

Sir recently we had import some LED Parts, from which some are duty free as per notification no 12/2012 custom amended by Noti no 14/2014 custom. so should we firstly pay duty ( BCD @ 10% + CVD @ 12.5%, Ecess @ 3%, SAD @ 4%) on all & then take refund OR directly clear the goods without paying duty? & what the procedure too??

Please guide