I hire a babysitter to watch my children from 1:30 to 4:20 in the afternoon. I come home at 4:20, a few minutes before shkia. I owe the babysitter $40. However, I realize that the only money that I have is a 100-dollar bill. No one has change. Am I obligated to give her $100 to avoid transgressing the biblical prohibition of delaying a worker’s payment? Is she obligated to procure change and return the $60 to me? How soon is she obligated to do so?
Another question: Somebody asks me for tzedeka, but the only money I have is a $100 bill. (Let’s say I know that the person is not a faker.) Am I obligated to give it to him to avoid transgressing the prohibition of not giving tzedeka?
Regarding paying the babysitter- If you can go to the bank and withdraw money or to give her a check, then do that. If there is someone that you can borrow the money from, then borrow it. If all else fails, and there is no way to cash the bill, then you are not obligated to give the babysitter the large bill. However if she is a person that you can trust that she will give you back the change, then it is a recommended thing to do, in order to be mekayem this mitzva d’orayso. However if she is not someone that you trust, then you don’t have to.
Regarding giving money to tzedakah, it is the obligation of the receiver of the tzedakah to make sure to give the giver his change, and if the doesn’t have change you don’t have to give him.
Ahavas Chesed 7-9, Minchas Tzvi 2-12, Mispat Shlomo pg. 100, Salmas Chaim 531.