What is a term for the process of receiving a letter requesting payment on an account?

The term that accurately describes the process of receiving a letter requesting payment on an account is billing. Billing refers to the action taken to issue a statement or a request for payment for services rendered or goods provided. In a healthcare context, billing often involves sending out statements to patients or insurers to collect payment for services.

While collection refers to the follow-up actions taken to retrieve overdue payments, it doesn't specifically address the initial request for payment, which is what billing captures. Reimbursement typically relates to the process of receiving payment back from an insurer or third party, and invoicing pertains to creating formal documents detailing the amounts owed, which also ties closely to but is not as specific as billing when it comes to general requests for payment. Therefore, billing is the terminology that directly relates to receiving such requests.