There is law that states you cannot get more than 80% of your average current earnings for the same month from both worker's comp or public disability benefits and Social Security disability. So there is an offset of Social Security if you received worker's comp or a worker's comp settlement for the same months. That may be the reason for the $18,000 offset. But that offset amount is not income to you.

And I agree with other posters about your tax preparer. Doesn't sound right to me either. But none of us have access to your tax records so we are just guessing.