My 25 year old son had no income last year. In fact it was minus $6,000 on his 1040 form. I was fully providing for him. His community college volunteers helped him file his taxes. On his 1040 he indicated that "no one could claim him as a dependent". Because of that, I didn't indicate him as a dependent on my last year's tax return.
This year I want to file a 1040x form for the last year and include him as a dependent. I assume he also needs to file a 1040x to indicate that "there is somebody who could claim him as a dependent". Does he? Does he also need to file a 1040x?