You can call the Social Security Administration to report the death of a Medicare beneficiary at 1-800-772-1213 (TTY 1-800-325-0778).
As noted on the Social Security Administration site:
report a death or apply for survivors benefits online. Social Security should be notified as soon as possible when a person dies. In most cases, the funeral home will report the person’s death to Social
Security. You should give the funeral home the deceased person’s Social
Security number if you want them to make the report."
If a family member or other person responsible for the beneficiary's affairs wishes to notify the Social Security Administration (SSA), they should do the following:
Promptly notify Social Security of the beneficiary's death by calling SSA toll-free at 1-800-772-1213 (TTY 1-800-325-0778) (between 7:00 AM and 7:00 PM
Monday through Friday).
Or the family representative can contact a local Social Security Administration office. Local SSA offices can be found using the link: https://www.ssa.gov/locator/
If monthly benefits were being paid via direct deposit, notify the bank or other financial institution of the beneficiary's death. Request that any funds received for the month of death and later be returned to Social Security as soon as possible.
If benefits were being paid by check, DO NOT CASH any checks received for the month in which the beneficiary died or thereafter. Return the checks to Social Security as soon as possible
One-time Lump Sum Death Benefit
A one-time payment of $255 is payable to the surviving spouse if he or she was living with the beneficiary at the time of death, OR if living apart, was eligible for Social Security benefits on the beneficiary's earnings record for the month of death (please see: https://www.ssa.gov/forms/ssa-8.html
and https://www.ssa.gov/planners/ survivors/ifyou7.html
If there is no surviving spouse, the payment is made to a child who was eligible for benefits on the beneficiary's earnings record in the month of death.
Benefits for Survivors
Monthly survivors benefits can be paid to certain family members, including the beneficiary's widow or widower, dependent children and dependent parents.
The following contain more information about filing for benefits.
Survivor Benefits: (Publication No. 05-10084) https://www.ssa.gov/pubs/10084.html (see also the Social Security Administration page at: https://www.ssa.gov/planners/ survivors/howtoapply.html).
Social Security: Understanding the Benefits: (Publication No. 05-10024) https://www.ssa.gov/pubs/10024.html
(Source: Social Security Online www.ssa.gov)
As reference, please also see:https://www.ssa.gov/survivors/