There is no subject criteria to study CA. If you want to study CA, you can study your 12th in an subject with any aggregate. You should have completed your 12th. For studying CA Foundation, you should complete mandatory 4 months of study period, register with ICAI and appear for CA Foundation exam directly. CA has 3 phases of study;Foundation, Intermediate and Finals. It takes 5-6 ears to complete the course. A CA as a fresher earns nothing less than 40k per month based on the nature of his job.