Like any legal document, the subrogation letter can be confusing if you aren't familiar with the term or the process. Click here to learn more about it!Authorization was issued as well as the information required to complete a claim form for billing purposes. Insurance companies can utilize this letter template to seek reimbursement from the person or entity legally responsible for a loss. I just received a subrogation letter from my health insurance. So they say that my young child had an injury that may have happened due to an accident. MUST complete the standard Health Insurance Claim Form 1500 and submit to Express Scripts via mail at: Express Scripts Pharmacy Claims. Alternatively, you can fill out the Form AR-1, which is a request for arbitration. Shortly after the initial insurance claims, I received the forms to fill out for subrogation. Mount Sinai South Nassau, located in Oceanside, NY, provides a wide variety of medical care and excels in cancer care and cardiac services.