I to have never provided my sin number.I had only 1 parent to date ask for it and thats fine ,but i give detailed reciepts with each date the child was here and the amount total amount for the day total amount for the week and total amount that receipt if its a biweekly payer.At the bottom of the receipt is my name my business name full adress and telephone number.I don't think your going to get fined unless if a parent requests it do to auditing and you refuse