Sample Letter to Bank Informing the Death of the Account Holder. The death claim letter should be written in the formal letter format.Here's a simplified guide on how to fill in an Affidavit of Death in nine steps: Step 1: Identify the Type of Affidavit of Death: You will also need to provide a certified copy of the death certificate. 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. Notify your loved one's financial institution(s) to retitle or distribute the account(s). I need to write to several organisations including banks, insurance and mortgager company to inform them of my partners death. Resources and information to assist in assuring firearm safety for families in the state of Michigan. Cancel benefits payments and close or transfer accounts.