If he can be claimed as a dependent under the rules, then you can claim him. If you had not yet filed your tax return, he could have filled out a “non-filer“ report to claim a stimulus payment as someone who does not file a tax return. However, this would have been improper on his part. If you are trying to file a tax return now, and you are blocked from claiming him as a dependent because of this non-filer report, you will need to print your return and file by mail. Your son you should return his payment, and the two of you need to have a discussion about honesty.
*Answers are correct to the best of my ability at the time of posting but do not constitute legal or tax advice.*
