My mother received a sizable deposit into her bank account from SSA. On her My Social Security website account it is only referenced as a One Time Payment.
Any thoughts of what this might be?
I have no idea why your mother would be due such a payment, but Social Security often makes adjustments of one sort or another that can result in a one-time payment of retroactive benefits due. The cause could be from additional earnings or some other type of recalculation that wasn't processed timely.
Your mother should receive a notice in the mail explaining the one-time payment within a couple weeks. If not, or if it isn't adequately explained in the notice, she may want to contact Social Security for an explanation.