There is 1% reservation for wards of Ex-Servicemen in NEET Counselling for the State of Tamilnadu. So you will need atleast 500 for a seat under this Category. This is just based on an observation of previous years cut offs. Now cut offs change every year. Cut offs change every year depending on various factors such as no.of Candidates appearing for the exam, no.of Candidates qualified, top NEET score and difficulty of the exam. So you should aim for atleast 500 for a seat under Ex-Servicemen Quota.