A medical assistant is reviewing a patient's balance on their account and notices a previous overpayment. The patient has come in for a new office visit which incurs a charge of $150. The patient's overpayment from the last visit is $200. After posting today's charges, what is the next appropriate financial action to take for this patient's account?
Apply the overpayment as a credit to the current charges and issue a refund for the remaining balance
Ignore the overpayment and require payment for the new charges in full
Keep the overpayment as a credit towards any future visits without issuing a refund
Increase the patient's current charge to use up the overpayment amount