Contact the Social Security Office at 800-772-1213. The line is open from 7 a.m. to 7 p.m. during the week; the same hours apply regardless of which time zone you are calling from. Have the deceased beneficiary's Social Security number available when you call.
Contact the deceased's bank to report the death. Banks require proof of death, such as a certified death certificate copy from the local vital statistics bureau. Ask the bank to return any money deposited in the account from Social Security from the month after the beneficiary's death forward. Social Security is one month behind, so if the person died in March, the benefit from March would be paid in April. Since the person died in March, you must return the money received in April for March.
Return uncashed checks from the beneficiary's death month or later to the local Social Security field office. Visit the official website of the Social Security Administration to locate the field office for the deceased person's address.