without a qualifying dependent, you go from head of household with dependent (lower tax rates and qualify for certain credits) to single (higher tax rates and may lose some credits) if all these tests are met:
the thing we can't answer because not enough information was provided is whether your son qualified to claim himself. here are the rules:
you can claim him as a qualifying child (dependent) and he must indicate that he can be claimed as a dependent on his return if all these tests are met
• he has the same principal abode as you for more than ½ the tax year. Temporary absences like for school are ignored
• if he is not a full-time student, he's under 19 at the end of the tax year. If a full-time student, he's under 24 at the end of the tax year.
• he hasn't provided over ½ his own support
• he didn't file a joint return unless there was no tax liability but merely filed jointly to facilitate refund of taxes withheld or estimates paid
or you can claim him as a qualifying relative if all these tests are met
• his gross income for 2021 is less than $4,300
• you provided over ½ of his support
• he isn't a qualifying child of another taxpayer
if either set of tests is met he must indicate that he can be claimed as a dependent on his return which would require him to amend his return if his return was accepted.
because of the duplicate SSN one of your returns should have been rejected when an attempt was made to e-file it.
to give the best advice as to what needs to be done we need to know if:
1) you qualify to claim him. if not, his return is fine
2) whose return was accepted and if it was his did you mail in your original return?
