For getting a mbbs seat in govt. Medical college in tamilnadu under obc category through all india quota counselling , try to score 530+ marks in neet ug exam. However for state quota counselling try to have score of 490+ marks in neet ug exam.
Good luck..

It's very difficult to determine cutoff scores prior to examination. However if we follow general trends, a score of around 500 should be enough to get a seat through state quota.

For obc category try scoring around 540+ mark in NEET and you will get a seat
A the best