Hello ,

As you are query is that you want to give NDA exam after the age of 20 sorry, but I would like to tell you that the age limit for giving NDA exam is in between 16.5 to 19.5 year is only so after the age of 20 as if you are now you can't give the NDA entrance exam and at that particular time you must be a 12th passout student aur going to be. 

I hope your query is solved. 

Thank you.