Hello,

To join NDA you have to be Unmarried and of age within 16.5 to 19.5 years.

UPSC releases the NDA application form twice every year at its official website: www.upsc.gov.in (http://www.upsc.gov.in/)

Please refer to the following site which will give you details regarding how to apply and the documents required, etc:

https://competition.careers360.com/articles/how-join-nda-after-passing-12th

Good Luck