The question is what happens when there is a problem with the SSN or other ID such that it isn't in the lookup table. I think that is the answer to your question.
Ron, there are more types of code than VBA. If you are writing SQL then that is also code in a 4th generation language. However, I digress.
I might have written this in two parts, with an employee table for which an employee ID is listed as the PK of the table - and SSN is generally a poor choice. It might be right for your case but technically, not everyone has an SSN. But if they work for your company, then everyone will have an employee number.
Anyway, if you have the Employee ID number field in the Employee table, you can write JOIN queries that will contain all the data you want and do that lookup automagically anyway. You can do this ENTIRELY through the query-builder grid. A lookup FIELD is trouble waiting to happen. A JOIN for your lookup is ALMOST a no-brainer and keeps your database simpler (in my personal opinion.)