Is it permissible for a woman to give her Zakat to her father if he is poor, and is she required to pay new Zakat for past years if she did so believing it was permissible?

The inability for the poor parents to receive zakat (definition) from their rich children, whether male or female, is due to the obligation of financial support. There is no impediment to giving zakat to poor siblings; in fact, it is better. Therefore, the woman must pay zakat for the past years during which she gave it to her parents, and she should be careful in estimating the amount. Zakat does not lapse due to the passage of time.