To become a Chartered Accountant, you need to pass 3 stages:

CA Foundation

CA Intermediate

CA Finals

CA Foundation: While there is no particular stream in which students should have pursued their studies, it is mandate to have passed 10+2 to be eligible for CA Foundation. There is a 4 month study period that is mandatory and needs to be completed before appearing for the exams. There are 4 papers in this exam and to be qualified its important to pass in all the papers with a minimum aggregate of 40% individually and a total aggregate of 50%. 2 papers are Objective type and 2 papers are Subjective type with negative marking for 2 papers. The subjects are Principles and Practises of Accounting, Business alaw & Business Correspondence and Reporting, Business Mathematics & Logical reasoning and Statistics, Business Economics & Business Commercial and Knowledge. For example, the score should be 40/40/40/40 in every subject and 50% overall. Even if a student gets 50% or above overall but doesnt get 40% in any one subject, he/she doesn't qualify. He/She is considered failed. And in the same manner, even if he/she passes all subjects but scores less than 50% over all, again he/she is considered failed. The 4 months training period should be able to equip the students with the required knowledge on all these subjects and that's the reason why it is not necessary to have a Commerce background in  10+2. The exams are held in May and November of every year.

CA Intermediate:  This is the 2nd level of becoming a CA. There are 2 routes for this phase. One is completing CA Foundation and the other is a direct entry.  Graduates/Post graduates of Commerce/Non Commerce background can directly join CA Intermediate provided they clear their qualifying examination with the required aggregate. You need to be  registered with ICAI for CA Intermediate for both the ways. There are 8 papers in CA Intermediate that are both Subjective and Objective type. And the same pass rule applies here as well. Should score above 40 in each subject with an average aggregate of 50%. The subjects are divided into 2 groups. Group 1 has Accounting, Corporate Laws and other Laws, Cost and Management Accounting, Taxation. Group 2 has Advanced Accounting, Auditing and Assurance Enterprise Informations Systems and Strategic Management  and Financial Management and Economics for Finance. For Direct entry Commerce Graduates,  it is important to have 50% aggregate in their qualifying examination and for Non Commerce Graduates, 60% aggregate is mandatory. And then there is a mandate period of Orientation period and study period. In CA Intermediate as well, the exams are conducted in May and November of every year.

CA Final: The Chartered Accountants Final Exam has 2 groups namely Group 1 and Group 2. Group 1 has Fiancial Reporting, Strategic Financial Management, Advanced Auditing and Professional Ethics, Corporate and Allied Laws. Group 2 has Advanced Management Accounting, Information Systems Control and Audit, Direct Tax Laws and Indirect Tax Laws. The eligibility is that you should have passed your CA Intermediate and registered with ICAI. You should have completed the mandatory 12 months Practical Training or Articleship or should be in the 12th month of training by the time of examinations. And the pass rule applies here as well. After the succesful completion of all these levels, you are now a qualified CA.