IRD?

[TaxmannEA]

I was contacted by a person whose brother was confined to a nursing home from 1976 until his death in 2005. This sibling had POA over the brother during this tiime. When he was first disabled, an application for Social Security Disability was filed. SSA did not approve the claim due to earnings history at that time. Now, 5 years after his death, the sibling receives a lump-sum deposit for the benefits for 1976 till 2005. (This is a very large amount.) I believe that this is income in respect to a decedant and must be reported on the return of the sibling who received the check. There has been no correspondence received from SSA in regards to this payment. Am I on the right track? I've never seen a payment made so long after the death of the claimant before.