The IRS states that the person(s) must reside with you or be a member of your household for a full year (12 months) period. Please refer to the IRS 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.