If you meet the conditions of the IRS test below, you will be able to claim your sibling on your income tax return. Since they resided with you for over 6 months, that question would be satisfied. Please keep in mind, that you will not be able to claim them if they file their own tax return and claim themselves.
A taxpayer may claim their child if they meet the qualifying child test as outlined below:
Qualifying Child
These 5 tests (all of them), will qualify a child as a
dependent:
-
Relationship: They
must be your child, adopted child, foster-child, brother or sister, or a
descendant of one of these (grand or nephew).
-
Residence: They
had to live with you in the same residence for more than half the year.
Being away at school is considered as living at home.
-
Age: Must
be under age 19 or under 24 and a full-time student for at least 5 months
of the year. They can be any age if they are totally and permanently
disabled.
-
Support: child
did not provide more than half of their own support during the year.
-
Joint
Support: The child cannot file a joint return for the year.
