Minimum age limit for X CBSE examination 2021

You are presently in class 9. Now you will apply for admission to class 10 in the next year that is 2020. As per CBSE guidelines your age as on 1st October 2020 should be 14 years or more. Then only you will be eligible to appear in exam for class 10 in the year 2021.

Now let us see your age as on 1st October 2020. Your date of birth is 16.08.2007 so your age as on 1st October 2020 is only 13 years and about 1-1/2 month. So you are falling short of the required stipulation.

Now you have one option that you can ask special age exemption from the board authorities but it is not so simple as they will be giving it only in some special cases and you have to find out the criterion from their office regarding this.

Another thing is you can drop in class 9 for one term and that way make up the age next year. In this you will be losing one precious year of your educational career. Regarding change of date of birth you should have some supporting document for that change like hospital birth certificate etc otherwise arbitrarily changing it with an affidavit will be a false claim. Please remember that if you do that then you will retire from the services one year earlier which will be a big loss at that time. So this option is to be exercised with caution.

If you are writing the 10th examinations in March 2021, you should complete your 14th year on or before 1.10.2020.
But in your case, you are having less age than required. So you may not be allowed to sit for the examinations in normal course.
But the board may consider reducing the minimum age limit. For that you have to apply to the board through the school you are studying with the recommendations of the Head of the school you are studying. You take your parents to the school and talk to the head of the institute so that he will tell you the way for this. This is the best course of action.
Changing the date of birth by giving an affidavit is not easy and you should have sufficient supporting documents. If there is any proof with you that there is a mistake in your DOB, you can go for an affidavit. Otherwise, it is not advisable.

In my knowledge you can apply CBSE exam 2021 if your age is 14 years or more than this on 1 October 2020.