At first blush, I would be conservative and advise your son to claim no exemptions on the W4. Especially if someone else claims him as a deduction. The more exemptions, the higher the chance your son owes taxes at the end of the year. However, to know for sure go to irs.gov. Under Forms & Instructions and download the W4 form. There are instructions and a worksheet included with the W4 that will guide you through the questions you need to answer to know the answer that is truly correct for your son.
