Hello aspirant,

Hope you are doing absolutely great.

So with regard to your query, in case if you fail just in one subject in the CBSE board exams then you will have one more opportunity in the form of compartment exams, where you can give the exam and pass it again. However, if you fail in two or more exams then you will be considered as failed and you should repeat the whole 12th standard again.

Hope this helps you,

Good luck, thank you.