Legal Question in Employment Law in Illinois

Do not withhold the money, unless you have a clear written agreement signed by the employee allowing you to do this. Your choices are basically, let it go, ask him nicely, hire an attorney, or sue him in small claims.

Pay him in cash with a receipt? Ask him if it's ok to do that? If you pay by check for accounting purposes, have him sign an ok and if not a "Demand" promissory note with interest under 9%. Then you go with him to his bank or currency exchange where he cashes the check and gives you your money (the signed note protects you from his trying to say you were not entitled to the money. Otherwise if he doesn't pay you back you can sue on the note and get interest and if properly drafted court costs and attorney fees which could triple the amount due easily.