Eligibility as per related Regulations is as follows:-

i. He/she has completed age of 17 years at the time of admission or will complete that age on or before 31st December of the year of his/her admission to the 1st year MBBS/BDS Course. 

ii. The upper age limit for NEET (UG) is 25 years as on the date of examination with relaxation of 5 years for the candidates belonging to SC/ST/OBC category and persons entitled for reservation under the Rights of Persons with Disabilities Act, 2016.     

The Age criteria for appearing in NEET (UG) - 2019 is as follows:

For Candidates of Unreserved Category (UR) born on or between 05.05.1994 and 31.12.2002

For Candidates of SC/ST/OBC/PwD Category born on or between 05.05.1989 and 31.12.2002 

This should help you.