hi from just answer.
My first guess is it was a mistake. Error in typing in your social security or EIN, then adding assessment. Your question didn't add a lot of detail, so keep that in mind.
Secondly, it sounds like a trust fund assessment could have been made against you, then removed/reclassed when either someone else was found liable or the taxes were paid, removing the need for the assessment.
If this covers your question, please click Accept. If you can provide more facts, such as did you own this business, type of taxes/periods, did you have employees, etc., that would help be more accurate.