Based on the information you've provided, it appears that you can claim your sister as a dependent on your return. See the requirements for Qualifying relative, below.
Generally, you can claim someone as a dependent if she meets the
following requirements as either a qualifying child or a qualifying relative.
Qualifying child
- ·
They are your child, stepchild, foster child or sibling, or
a descendant of any of these.
- ·
They aren't being claimed as a dependent by
someone else.
- ·
They are a U.S. citizen, resident alien,
national, or Canadian or Mexican resident.
- ·
They aren’t filing a joint return with their
spouse.
- ·
They are younger than you, and under the age of
19 (or 24 for full-time students). If
the person is permanently and totally disabled, there is no age limit.
- ·
They live with you for more than half of the
year (exceptions apply).
- ·
They didn’t provide more than half of their own
support.
Qualifying relative
- ·
They don't have to be related to you.
- ·
They aren't being claimed as a dependent by
someone else.
- ·
They are a U.S. citizen, resident alien,
national, or a Canadian or Mexican resident.
- ·
They aren’t filing a joint return with their
spouse.
- ·
They either lived with you the entire year, or
they were related to you.
- ·
They made less than $4,050 in 2017.
- ·
You provided more than half of their financial
support.
Your sister probably doesn't meet the standards of Qualifying child because of her age, but she appears to meet Qualifying relative requirements, based on the limited information..
For additional details, see Table 5, Overview of the Rules
for Claiming an Exemption for a Dependent, in IRS Publication 501,
Exemptions, Standard Deduction, and Filing Information .
