Claim your son on your own tax return. You get the $500 credit for other dependents, education credit, possibly earned income credit and if you are a single parent --Head of Household filing status. If he had any tax withheld from his paychecks he can file a return himself to seek a refund of the amounts in box 2 or box 17 of his W-2. He must say on his own return that someone else can claim him as a dependent.
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