Redeeming a 3 month prepaid card

Time you redeem via prepaid cards is fully added to whatever time is left on your son's account (up to 36 months).

So for example if your son has still 3 months of Gold left on his account, and you add a 12 month card, your son has 15 months of gold on his account.

Or if your son has an active subscription, and his subscription would renew in 3 months from now, and you add the 12 month card, the prepaid card will "pause" his subscription, activate 12 months, and after the 12 months of the card are over, the subscription
will continue with the remaining 3 months, and your son will have to be billed again in 15 months from now.

So there really is no need to wait until you redeem prepaid cards.

In fact, since some promotional cards have an expiry date on them, I heartily recommend to redeem prepaid cards as soon as possible.

But keep in mind, that you can have only up to 36 month of Gold or Game Pass time on your account.

Indeed, token stacking works on a recent-first basis. The most recent membership you purchase or redeem is what is consumed first. If you have 3 weeks remaining on a 12-Month membership, and you redeem a 3-Month prepaid card, then after 3 months, those
remaining 3 weeks kick back in and it's business as usual. Peculiarly, if you have a 1-Month membership set to auto-renew, and you redeem a prepaid code, it will turn off automatic renewal. In other cases, if you had a renewing membership, but you turned
off auto-renewal, and you then redeem a prepaid card, this can turn your auto-renewal back on, as the prepaid card tells the system that you're not interested in canceling afterall. Therefore, it's always a good idea to go to Xbox.com/account after you've
set up your Gold, to make sure that the automatic renewal is in the state in which you desire it to be, on or off.

G'day Smoky! Please start a new thread and offer up some details as to what's going on. What is the exact error message that appears? Have you tried redeeming on xbox.com and on your Xbox 360 console? Is all of your billing info up to date at
commerce.microsoft.com? Let us know and we'll be happy to help.

DId you enter in the right code.

If your account is locked you would need to contact phone support to speak to billing so they can help you get it unlocked. 1-800-4my-xbox if you're in the US/Canada.