@DoninGA @rich5674
<<The person must not file a joint return with their spouse.>>
The inference here is that the OP can't claim their parents due to the statement above.
However, the OP states that the parents have no income other than SS.
Therefore, they are NOT filing a joint return; in fact they are not filing a return at all!
The OP can claim their parents, as long as the other conditions are met.
from publication 501:
"You can't claim a married person who files a joint return as a dependent unless that joint return is filed only to claim a refund of withheld income tax or estimated tax paid."
Please see page 11 - 2nd bullet:
www.irs.gov/pub/irs-pdf/p501.pdf
