Sample Letter to Bank Informing the Death of the Account Holder. The death claim letter should be written in the formal letter format.You'll need the person's Social Security number and certified copies of their death certificate for most agencies and programs. Social Security and Medicare. The letter should cover the following: The following checklist may help guide you through the matters that must be attended to upon the death of a family member. You will also need to provide a certified copy of the death certificate. Documents we'll need: Copy of the death certificate. Letter of instruction. The name of the deceased person.