Is it permissible to offer the fidyah of feeding a poor person on behalf of a deceased mother before paying the accumulated Zakat on money?

Zakat (definition) must be paid as soon as it becomes due. It is not permissible to delay it except for a valid excuse, such as dire need. Delaying it while having the ability to pay is a sin. If there is overdue zakat, it must be paid promptly before any voluntary acts, such as paying the fidyah (definition) on behalf of the mother, for zakat is obligatory, and the principle for obligations is immediate fulfillment.