Hey Vincent!
Nice to meet you! I'm Darhyl, an Independent Advisor.
To answer your inquiry, according to Independent Advisor Gerardo CG: https://answers.microsoft.com/en-us/xbox/forum/...
"You can purchase subscriptions with the balance in your Microsoft account obtained from gift cards. However, to do so, you need to link an additional backup payment method to your account, such as a credit/debit card or a PayPal account.
This is because subscriptions involve recurring payments, and therefore, you must have another payment method as a backup.
These terms and conditions are mandatory and set by Microsoft. But don't worry, you can cancel the automatic renewal at any time after purchasing your subscription.
This means that you won't be charged automatically when it expires. Once you have the balance in your Microsoft account and have linked a credit card, debit card, or PayPal, you can select your account balance as your primary payment method. When asked how you want to pay the rest, you should choose the payment method you associated previously.
You won't be charged anything, except for a small verification fee, which is automatically refunded after a few days. "
Thank you for your kindness and understanding! Please feel free to let me know if you need anything else.
Best regards,
Darhyl