Hello,
The info we got through Tamil Nadu Site where vehicle cost is more than 10 Lakh
Below would be the cost of re-registration Road Tax to be paid based on Invoice value of the car
1. Less than 1 year : 13.75% of the total cost of the vehicle
2. More than 1 year but not more than 2 years : 13.50% of the total cost of the vehicle
3. More than 2 year but not more than 3 years : 13.25% of the total cost of the vehicle
4. More than 3 years but not more than 4 years : 13% of the total cost of the vehicle
5. More than 4 years but not more than 5 years : 12.75% of the total cost of the vehicle
6. More than 5 years but not more than 6 years : 12.50% of the total cost of the vehicle
7. More than 6 years but not more than 7 years : 12.25% of the total cost of the vehicle
8.. More than 7 year but not more than 8 years : 12% of the total cost of the vehicle
Source URL - http://www.tn.gov.in/sta/t10.html
apart from it - there could also be entry tax which may be applicable - requisite info can be obtained from RTO Office
Hope should help