Is zakat to be paid as calculated at the beginning of the year on the entire amount in both currencies, or is it to be recalculated at the end of the year based on the change in the value of the local and foreign currencies?

Monetary currencies must be assessed when zakat (definition) becomes due, which is upon the completion of a hawl (lunar year) on wealth that has reached the nisab (definition), and not at the beginning of every year. Foreign and local currencies are to be valued by gold or silver. The nisab is the equivalent of 85 grams of gold or 595 grams of silver. One-quarter of one-tenth (2.5%) must be given. If the exact amount of zakat cannot be ascertained, one should act upon what is most likely, while striving for accuracy.