Is it permissible to give surplus money saved in the bank as charity to one's parents for building or medical treatment, knowing that one is not obligated to spend on them?

The questioner is thanked for his diligence, and two points are brought to attention: First, nothing should be asked of Allah except Paradise. Second, ensure that the bank is Islamic, because depositing money in interest-based banks is unlawful (haram). As for zakat, it is obligatory on saved money if it reaches the nisab (minimum threshold) each year. It should not be given to parents or grandparents because their maintenance is a religious obligation, except in exceptional cases where their maintenance is not obligatory. However, giving charity to them from the principal amount is better than giving charity to others. If the money is from usurious interest, it must be disposed of by spending it on the welfare of Muslims, such as the poor and needy. It is permissible to give it to poor parents if the zakat payer is unable to provide for them.