Hi there, William59! If you are enrolled in monthly Auto Re-Boost, the entire cost of your monthly plan is automatically charged to your registered credit or debit card, even if you have money in your account balance.
Any money you have in your account balance can be used for services that aren't covered in your monthly plan, such as ringtone or game purchases, international calls, etc.
But as long as you have a credit or debit card registered with Boost and you are signed up for Auto Re-Boost, your credit or debit card will be charged the full cost of your monthly plan regardless of how much money you have in your account balance.
Understood! @William59, You can use your account balance by purchasing data packs, or add-ons such as (International calling, hotspot, etc...). However, You will need to remove your card from the auto pay option, and the account will take amount on the account balance.