the only remedy is for both of you to file amended returns. he files first noting he could be claimed as a dependent. then, because the IRS is so far behind in processing returns I would wait a month before filing your amended return. what you don't want to have happen is for the IRS to get to yours first and reject it because it sees your son is still claiming himself. I certainly would included in the explanation of the reason for amending on your return a statement that your son will be filing his own amended return because he could be claimed as a dependent.
before filing the amended returns you both should make sure that there is an actual tax savings because his taxes could go up more than yours goes down.
