I learned today that BOA had no lower age limit for authorized users so I put my youngest on a card (elementary school), but I do not plan to give him access to the card. The idea is that when he does want credit, he will have a long history.
If you anticipate that your child will actually use the card, it may pay to pick one with a low limit as a safety device. Since the limits on the cards show, it might be wise to make the children authorized users on high limit cards but keep these cards away from them, locked up somewhere.
Indeed it may pay to make them authorized users on a number of cards so that their record in the future looks good.
I believe AMEX has a 16 age year limit for their cards so this would not work with them. Amex lets you set limits for authorized users, which can be useful where you want the child to be able to spend, and earn points for you, but want to limit the risk.
I do not know rules for other issuers. Does anyone?
Does anyone know whether the original opening date for a card appears on the authorized user credit reports, since this might affect the card chosen.