there is no requirement to claim a qualifying dependent assuming he is. since we can't see your return or know anything about either of you we cannot know if you'll be overpaying your taxes by not claiming him. however, if you are not considered married without a qualifying dependent you would have to file as single not head of household, and would likely be paying more in taxes. On your son's return, if his only income was from the NEC, amending to indicate he could be claimed PROBABLY would not affect his taxes but again we can't see his return. if you claim your son you will have to mail in your return and he will have to amend his return.
