Hi Anurag,

According to the latest eligibility criteria of NDA Examination, a student should be 16.5 years - 19.5 years of age to be eligible for NDA.

For NDA I, his DOB should be between July 2, 2002, to July 1, 2005.

For NDA II, his DOB should be between January 2, 2003, to January 1, 2006.

In your case, your DOB is  8 december 2003, so you are eligible to appear for both NDA I and NDA II in 2021. In NDA 2022, you will only be eligible to appear for both NDA I and not for NDA II.

Refer here for more info - UPSC NDA Eligibility Criteria 2021 - Age Limit, Qualification, Nationality, Marks (careers360.com)

Feel free to ask doubts in the Comment Section.

I hope this information helps you.

Good Luck!