$25 charge to create User account?

New to Xfinity internet. Wanted to add a mailbox for my wife. Went thru steps to send an invitation. She responded to the email and completed some form. Xfinity seems to have at least partially set up an account for her. Then Xfinity said it was processing a $25 charge. She had not entered a credit card, so I don't know if we've been charged on my account. Is there supposed to be a $25 charge? If so, is it one-time? Did we do something wrong?