Answered by Shaykh Faraz Rabbani
If I received a lump sum of money say two months before the payment of zakat was due on the rest of my savings ,the is zakat also due on this lump sum at the same time or does a year have to elapse on it before payment is due, and therefore I only pay zakat on my existing savings

Walaikum assalam,
If you owned the zakatable amount at the beginning and end of the zakat period (hawl), then you have to pay zakat on the entire amount you possess at the end of the zakat period, whether or not you actually possessed the whole amount for the whole period. [al-Hadiyya al-`Ala’iyya, Hashiyat Ibn Abidin]
Wassalam,
Faraz Rabbani