Hello Aspirant

According to NEET guidelines the aspirant must have completed 17 years of age before they sit for the exam

so the candidate must have completed 17 years of age before 31 December 2020 for applying for the exam there is no upper bar that is mentioned for giving the exam.

so in short you must have attained 17 years of age before taking the admission or will be attaining the same before 31st

Regards!