12th boards marks are not counted in calculating your NEET Score but they are needed to help you appear for the exam.

NEET Score is the sole basis to help you fetch your MBBS seat.

The class 12th Boards marks does not have any impact on the medical aspirant's position in the merit list of the medical colleges.

The only criteria that a candidate need to fulfill :

• The candidate must have passed in Physics, Chemistry, Biology and English individually.
• The candidates belonging to General Category should score a aggregate minimum of 50% marks in Physics, Chemistry and Biology in their Class 12 or HSC examination.
• Candidates who belong to Scheduled Caste/Scheduled Tribes or Other Backward Classes (OBC) should score a aggregate minimum of 40% in Physics, Chemistry and Biology in their Class 12 or HSC examination.

The same goes for AIIMS, JIPMER , JEE. 

Hope this helps