the same person can not be claimed as a dependent on two returns. if both are e-filed the second will be rejected. if the second is mailed both parties will get a notice from the IRS asking them to amend. if neither does (and only the person who is not entitled to claim the dependent should amend ) then the IRS will send a second notice asking for proof. the loser gets a bill for taxes, penalties and interest.
You could be claimed as a qualifying child if all these tests are met
• You have the same principal abode as the other party for more than ½ the tax year. Temporary absences like for school are ignored
• If not a full-time student, you’re under 19 at the end of the tax year. If a full-time student under 24 at end of tax year.
• you haven't provided over ½ your own support
• you didn't file a joint return unless there was no tax liability but merely filing joint to facilitate refund of taxes withheld or estimates paid
Or as you could be a qualifying relative if all these test are met
You’re related to the other person or, if not, lived with the other party for the entire year and
• your gross income for 2020 less than $4,300
• the other party provided over ½ your support
• you aren't a qualifying child of another taxpayer
if the parent is eligible to claim you as a dependent they get the education credit.
