- The 18-year-old must be your son, daughter, stepchild, foster child, or a sibling who is younger than you and under the age of 24.
- The 18-year-old must have lived with you for more than half of the tax year.
- The 18-year-old must not have provided more than half of their own support for the tax year.
- The 18-year-old must be enrolled in high school or equivalent full-time for at least five months of the tax year.
If you meet all of these requirements, you can claim the 18-year-old as a dependent on your tax return. To do so, you will need to provide the following information:
- The 18-year-old's name, Social Security number, and relationship to you
- The 18-year-old's date of birth
- The 18-year-old's school name and address
- The number of months the 18-year-old attended school full-time during the tax year
You can claim the 18-year-old as a dependent on your tax return even if they are not your biological child. For example, you can claim a stepchild, foster child, or a sibling who is younger than you and under the age of 24 as a dependent if you meet the other requirements.
If the 18-year-old is married, you cannot claim them as a dependent on your tax return. However, if the 18-year-old is unmarried and meets all of the other requirements, you can claim them as a dependent even if they are not living with you.