I have been hoarding foreign currencies for a year. However, its current value decreased from that of the time it was purchased so how should its zakat be paid?

All perfect praise be to Allaah, The Lord of the worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and messenger.

A decrease in the value of currency does not change the ruling of zakat as long as it reached the Nisaab that equals eighty-five grams of gold or five-hundred and ninety-five grams of silver.

If it reached this Nisaab alone or in addition to other currencies or trading goods, then it is obligatory to pay zakat on it. In principle, it is obligatory to pay zakat in the same form of wealth. In other words, if you possess dollars then you have to pay zakat in dollars, but there is nothing wrong with paying it in another currency, for example paying it for dollars in riyals. What counts is its value at the time of paying the zakat.

Allaah knows best.