Ph.D

No it is not all mandatory to take a joint M.Sc PhD after qualifying for IIT JAM. Although many students choose this, you can just apply for M.Sc now and if you feel apply for PhD later.

For GATE also the similar thing is followed.

After completing the PhD in CSE course, you can find good work opportunities in academia, tech companies, R&D units, etc., with excellent earning potential. Here are a few top recruiters for your reference:

• Google 
• Amazon
• Microsoft
• Deloitte
• Infosys
• Adobe
• IBM Global Services

The average tuition fee for studying the PhD in CSE course at top colleges is between INR 50,000 and INR 5 lakh. The cost varies on the basis of the college where you're planning to study the course, the college location, All India reputation, placements, and industrial connections. Apart from the tuition fee, you also need to check for extra charges for hostel facilities, college application, semester exam registration, lab work, etc.

The PhD in CSE coursework requires you to study some foundational coursework that includes the fundamentals of research methodology and professional academic writing, literature review, qualitative and quantitative research, workshops, seminars, and final thesis writing. This does not allow you to customize any subject module.

Having said that, the rest of the coursework modules are in accordance with the chosen research area, where there is scope for customization. You have to conduct detailed research on a specific topic under the supervision of your supervisors and present a thesis at the end of the PhD course duration.

When it comes to the PhD in CSE entrance exam, you should start your preparation as early as possible, at least 8 to 10 months before the final exam is tentatively scheduled to take place, so that you have a good amount of time to cover all the exam syllabus topics, practice last year's question papers, and revise the important concepts in the last month.