My adult sibling and her child lived with me more than six months. Can I file a dependent claim for them?

Maybe.

Your sister is your qualifying child if:

• She’s one of these:
  • Under age 19
  • Under age 24, a full-time student, and younger than you (or your spouse, if married filing jointly)
  • Permanently and totally disabled and any age
• She lived with you more than half of the year.
• She didn’t provide more than half of her own support for the year.
• She’s not filing a joint return unless it’s only to claim a refund of taxes withheld. So, neither she nor her spouse would have had any tax liability if they had filed separate returns.

If she doesn’t qualify as your qualifying child, your sister is your qualifying relative if these are true:

• Her gross income for the year is less than $4,700.
• You provided more than half of her support for the entire year.
• She’s not filing a joint return unless it’s only to claim a refund of taxes withheld. So, neither she nor her spouse would have had any tax liability if they had filed separate returns.

You can claim your sister’s child if you can claim your sister as a dependent and the child meets these tests:

• The child is one of these:
  • Under age 19
  • Under age 24, a full-time student, and younger than you (or your spouse, if married filing jointly)
  • Permanently and totally disabled and any age
• The child lived with you more than half of the year.
• The child didn’t provide more than half of his or her own support for the year. It doesn’t matter who supported the child as long as the child didn’t support himself or herself.
• The child isn’t using married filing jointly unless it’s only to claim a refund of taxes withheld. So, neither the child nor the spouse would have had any tax liability if they had filed separate returns.

If your sister is your dependent, she can’t claim any dependents of her own, including her child.

If you can’t claim your sister as a dependent, she’ll be able to claim dependents and can likely claim her child as a dependent. In this situation, it’s possible your sister’s child is the qualifying child of both you and your sister. You both must meet the four tests listed above.

If your sister’s child is the qualifying child of both you and your sister, then you’ll need to consider certain tie-breaker rules. As the parent, your sister will have the stronger claim to her child’s dependency exemption, but she doesn’t have to claim to the child. You can claim her child if your adjusted gross income (AGI) is higher than your sister’s AGI, and she doesn’t claim him.