There are two types of dependents, "Qualifying Children"(QC) and Other ("Qualifying Relative" in IRS parlance even though they don't have to actually be related). There is no income limit for a QC but there is an age limit, student status, a relationship test and residence test.
A child of a taxpayer can still be a “Qualifying Child” (QC) dependent, regardless of his/her income, if:
- He is under age 19, or under 24 if a full time student for at least 5 months of the year, or is totally & permanently disabled
- He did not provide more than 1/2 his own support. Scholarships are excluded from the support calculation
- He lived with the parent (including temporary absences such as away at school) for more than half the year
So, if you are over 18 and not a full time student, you cannot be a QC. There is a $5200 income test that determines if you can be claimed as a qualifying relative dependent. The $5200 is not limited to earned income.
This question usually comes up in determining who gets to "claim the 1098-T" for the generous education credit, because of a special rule that limits college age students from claiming it.* The simple answer is: you get to claim it (even if you are under 24) since you are not a full time student and do not qualify as your parent's dependent.
*There's a new urban myth among college students that says they can get a $1000 from the government just for filing a tax form. For most of them, they simply aren't eligible. A full time unmarried student, under age 24, even if you don't qualify as a dependent, is only eligible for the refundable portion of the American Opportunity Credit if he supports himself by working. You cannot be supporting yourself on parental support, 529 plans or student loans & grants. It is usually best if the parent claims that credit.
You cannot claim the (up to) $1000 refundable credit if you are, or can be, claimed as a dependent by someone else.
Reference: Line 7 instructions for form 8863.
https://www.irs.gov/instructions/i8863#en_US_2024_publink53002gd0e674
https://www.irs.gov/instructions/i8863
