You would be able to claim your mother as a dependent as long as:
- her gross income (not including nontaxable social security benefits) is less than $5,050
- you provided more than half of her support (housing, food, medical care, transportation, etc)
- only you are claiming her as a dependent (if other people also help support her and you did not provide more than half of her support yourself, you would need them to agree that they won't claim her)
The fact that she lives with you and you provide her housing and transportation works in our favor for the support test. Social security and Medicare don't count toward the gross income test but they do count when calculating support. You'll need to add up all of the support you provide to make sure you provided more than half. The IRS has this worksheet for determining support that is very helpful for figuring out if you qualify.
