A person can still be a standard dependent ("Qualifying Relative" in IRS parlance even though they don't have to actually be related), if not a Qualifying Child, if he meets the 6 tests for claiming a dependent:
1. Closely Related OR live with the taxpayer ALL year
2. His/her gross taxable income for the year must be less than $4,050 (2016-17). Social Security does not count as income
3. The taxpayer must have provided more than 1/2 his support
4. He must be a US citizen or resident of the US, Canada or Mexico
5. He must not file a joint return with his spouse or be claiming a dependent of his own
6. He must not be the qualifying child of another taxpayer
Social
security doesn't count as income, for the income test, but social security
money he/she spends on her self does count as support not provided by you, for
the support test. The IRS has a worksheet that
can be used to help with the support calculation. See: http://apps.irs.gov/app/vita/content/globalmedia/teacher/worksheet_for_determining_support_4012.pdf The support
value of a home is the fair market rental value, divided by the number of
occupants.
In TurboTax, you enter the dependent's info under personal info and carefully answer the dependent interview questions.