To be claimed as your dependent, your child must meet the qualifying child test or the qualifying relative test. While the child’s age is a factor in the qualifying child test, it is not in the qualifying relative test. An individual meeting the qualifying relative test may be of any age.
As long as all of the following tests are met, you may claim a dependency exemption for your child:

• Qualifying child or qualifying relative test,
• Dependent taxpayer test,
• Citizen or resident test, and
• Joint return test.