Is Form 112 needed to be filled up

 Hey Guys....

                        Do i need to fill up 112 form as i want to pursue CS also side by side... i want to register myself befor november 30.....so tht i can give atleast one group.... in June... Pl help Out..and whn should i fill up the form after registerin or before registerin

or any formalities tht needs to be done.......

Thanks....!!!!!