SSY Contribution and Redemption Age?

[Sarthak2005]

What's the Age Till which we Can Contribute to SSY? (And What Basis is it Calculated) (Suppose My Sister's age is 13 Years, and Her Birthday Comes in April Month, so is the Contribution age Limit Calculated on Correct age or FY to FY Basis)
And What's The Age of Redemption?

 

[Sarthak2005]

The Link You Sent States That "Contribution is Allowed upto the end ot 15th Year from opening of account.

So Suppose i opened a Account for a girl at her 9th age
so I'm Allowed to Contribute for 15 years (9+15=24) Years
Or is it Allowed till 15th Birthday? (15-9=6) More 6 Years?

Which one of above is Considered and is Correct?