In css they go 4 basic concepts of only macro,development n micro while in M.A. we hv to focus on other fields as well .The B.A level knowlege is enough........only if u have really kNOWLEGDE of economics......currnet situation n latest trends in economics...............if u r going for M.A economics first than it wud be a gud option to take it as optional in CSS.......just always try to make a conceptual approach 4 the subject n develop ur interest......relate the theories with practice n current situation then economics wud give u gud score in css as well.........u dont need to prepare more after M.A.