Who is financially responsible for zakat?
Those for whom such a person is responsible financially are divided into four groups:
(1) One’s wife (provided she is not working),
(2) One’s ascendants [such as one’s father, grandfather, great-father, etc.].
(3) One’s descendants [such as one’s sons, daughters, grandchildren, etc.], be they male or female, young or old. However, one is not obliged to pay zakat on behalf of one’s ascendants and descendants unless they are poor or needy, even if their poverty is due to their being engaged in the pursuit of knowledge. As for an older descendant who is not engaged in the pursuit of knowledge, he must be incapable of earning a living [in order for zakat to be paid on his behalf].
(4) Those who are ‘owned’ and are in the service of the person, such as slaves, even if they are fugitives or captives.
Source: Fiqh1 (According To The Shafi’i School Of Islamic Law), Erkam Publications