We can use the 3 months Voucher value Rs,599 to renew for the annual prime membership as well..
It is not just restricted to renewing for just 3 months Prime Plan...
I got offer to renew for 1399 for this year( as usual) , I used 599 from my 3 months voucher that I bought before and Rs800 from my Gift card balance..
I redemed 3 moth prime and after few minutes I added 1499 prime voucher and redeemed 1 year prime. I only got ₹300 cashback as youth offer and didn't got cashback for yearly prime.