What are the outlets for money mixed with usury, and is it permissible to give it to one's fiancée to prepare herself for marriage or to use it in building a mosque?

It is not permissible to deposit money in interest-based banks except out of pressing necessity or in the absence of legitimate alternatives. When there is a need, it is permissible to deposit money in them, but the interest-based earnings must be disposed of and spent on the welfare of Muslims, such as building and maintaining mosques. It is not permissible for an individual to benefit from it for himself or for those whose maintenance is obligatory upon him, unless he is poor, in which case he may take according to his need. It is permissible to give it to a poor fiancée or her poor father. However, if she is rich, or if the purpose is to protect the person's own money, then it is not permissible to give it to her.