You can consider below points -

Domicile residents of Tamil Nadu should have qualified 8th, 9th, 10th and 10+2th standard in the state.
If the domicile residents have completed their 8th, 9th, 10th and 10+2th standard from outside the state, then they will also be eligible provided they bring their copy of nativity certificate.
Children of government employees whose parents have been serving the state for the past 5 years from the day of application will also be eligible even if they are not domicile residents.
The children of All India Service Tamil Nadu cadre officers will also be termed eligible for admission.

To know about the TNEA eligibility criteria, you can go through the below link -

TNEA Eligibility Criteria 2017

Hope this helps!!!