Hi Manish Kumar,

NDA Age Limit Criteria 2020 is as follows:-

Only unmarried male candidates born not earlier than July 02, 2001, and not later than July 01, 2004, are eligible to apply for NDA (1) 2020.

The date of birth mentioned in the Matriculation or Secondary School Leaving Certificate will be accepted by UPSC. These certificates are required to be submitted only after the results of the NDA written exams are declared.

As your son is born before 2nd July 2001 he is ineligible to apply for the NDA Examination.

You can refer to this article for more information:-

NDA Eligibility Criteria 2020

I hope it helps you.