No your mother's social security is not considered income for the income test. However, her SS is considered when determining if you provided over 50% of her support. Please see the IRS conditions for the Qualified Relative test below:
Qualifying Relative
These 4 tests (all of
them) will qualify a relative as a dependent:
- Not Qualifying Child: They are not
your or another taxpayer’s “qualifying child”
-
Gross
Income: Dependent has to
earn less than $4,050 in 2016.
-
Total
Support: You provide more
than half of the total support for the year.
-
Member
of Household or Relationship: The
person (a friend, girlfriend, non blood relative) must live with you all
year as a member of your household or be one of the relatives that doesn’t
have to live with you (mother, father, brother, sister, aunt, uncle,
stepmother, stepfather, your child, stepchild, foster child, adopted
child, etc) Note: this list is not all inclusive.