Ruling on giving voluntary charity to a sister.

Question:
A man who is an engineer asks: What is the ruling on giving voluntary charity to a sister as long as she is in need?

Answer:
Answer: If the sister is in need of financial maintenance and there is no heir between you and her who would block your inheritance if she died, such that you could inherit from her, then you give her from your wealth to maintain her, but you do not give her zakah; because her maintenance is obligatory upon you (and upon the heir likewise). So you maintain her from your wealth and do not give her zakah. However, if you are blocked from inheriting from her on the side of inheritance, meaning you do not inherit from her, and she is in need, then you maintain her and give her zakah.