For automatic payments:
If you'd like your credit or debit card used to pay your account costs automatically, you can assign it to be your primary or backup form of payment. Learn how to assign a form of payment.
If you want to decide each time you use your card, you can simply keep it in your account without assigning it. You can then choose to use it any time you use the Make a Payment feature. However, your account must have a primary form of payment.
For manual payments:
You can choose to use your credit card any time you use the Make a Payment feature.