Hi Aspirant, with regards to your question I want to mention that as per the official eligibility criteria for MCAT 2021:-

• Any candidates interested in pursuing career in Allopathic, Osteopathic, Podiatric and Veterinary can appear for the MCAT test.
• Students from U.S. and Canada must have a UG degree to be eligible for the exam.
• International candidates must be pursuing or have completed MBBS to sit for MCAT.
• Students taking MCAT for purposes other than pursuing a career in medicine are required to get special permission from AAMC authorities.

You are eligible to apply for MCAT after 12th but its not recommended. Hope this helps

Thanking you

Yours sincerely

Somenath