Hello!
The rules for changing your stream from Class 11 to Class 12 state that:
1. You can change with the permission of the Head of the School but not later than 31st October of that academic session.
2. After passing Class 11, you cannot change your stream.
3. You shall not offer a subject in Class XII which you have not studied and passed in Class XI.
4. However, the CBSE Chairman shall have the powers to allow a change in subjects to avoid undue hardship to the candidate, only if such a request for change is made before 30th August.
For further information, please refer to this link:
https://school.careers360.com/boards/cbse
Best wishes
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