Age is a factor in the qualifying child test, but not the qualifying relative test. . As long as the following dependency exemption tests are met, you may claim him or her:

1. Qualifying child or qualifying relative test;
2. Dependent taxpayer test;
3. Citizenship or resident test; and
4. Joint return test.

Refer to Publication 501, Exemptions, Standard Deduction and Filing Information, or Tax Topic 354 , Dependents for more information.

References:

• Publication 501, Exemptions, Standard Deduction and Filing Information
• Tax Topic 354, Dependents

Source: www.irs.gov