Since your mother has pension income (in addition to Social Security) that is over $3,400, you cannot claim an exemption for her as your dependent. If her income was below this threshold, you would need to pay for at least half of her living expenses to claim her as your dependent. You would not include her income when you file your return. If you are paying for more than half of her expenses including medical expenses, you may be able to deduct the medical expenses along with your medical expenses. You would still only be able to deduct medical expenses that exceed 7.5% of your Adjusted Gross Income.