Is the zakat on money forfeited for the first nine months if the amount decreases before the end of the year, and a new year (hawl) begins for the remaining amount? Or is zakat paid for the nine months on the full amount, then for the remaining three months on the reduced amount? Or is zakat paid for the entire year on the original amount?

Whoever possesses wealth that reaches the nisab (definition) (minimum threshold) and a full hawl (lunar year) passes over it without its diminishing below the nisab during that time, zakat (definition) becomes obligatory on what remains of it at the completion of the hawl, even if a part of it was spent during the year, provided that it did not fall below the nisab. As for the wealth that was spent before the completion of the hawl, there is no zakat on it.