Is it permissible to take payment from the mother's money in exchange for her care?

The basic principle is that it is not permissible to take a wage for serving one's parents, because it is an obligation upon children and part of the righteousness enjoined by religious law. One who fulfills a right that is due from him to another is not permitted to take a wage for it. However, taking something from the mother to provide for her needs of food, drink, or clothing is permissible, because it is not obligatory for the son to spend from his own money on his mother if she has enough to suffice her. So, if you intend to take from your mother's money to provide for her future needs, or as a reimbursement for what you previously spent on her with the intention of being repaid from her wealth, there is no harm in that. As for what has passed and what you spent on her as a donation from yourself, it is not permissible to take compensation for it from her salary, due to the Prophet's (peace be upon him) saying: "The one who takes back his gift is like a dog that returns to its vomit."