Yes, it could be from an underpayment in a previous
year. Or, sometimes it may be a
retroactive payment for prior years when Social Security benefits are just
getting started.
There should be an amount listed on your Form SSA-1099 in
box 3 with an asterisk (*) beside the dollar amount. Then, at the bottom of the page in the box
showing “Description of Amount in Box 3”, there is an explanation for the
previous year amounts paid.
