* Relationship Test: They must be your qualifying child or qualifying relative.
* Support Test: You must provide more than half of their financial support for the year.
* Residence Test: They must have lived with you for more than half the year (exceptions exist for students).
* Citizenship/Residency Test: They must be a U.S. citizen, national, or resident alien, or a resident of Canada or Mexico.
* Student Test: They must be a student for at least five calendar months of the year.
The key here is that age is not the determining factor. Even a student over age 24 can be claimed as a dependent if they meet all the other requirements. The student's full-time student status helps satisfy the residence and support tests. However, it's crucial to carefully review all the rules on the IRS website to ensure eligibility in your specific situation.