No law establishes how old authorized users must be, but some credit card companies set the minimum age at 15 or 16 ... to buy a car, or to get a mortgage on a home. Debit cards do not affect ...

pointed out that the legal age for getting a debit card from a bank or credit union is 18. However, he said that if your child is under 18, you can get a debit card issued to your child ...