If I pay college costs and student loan interest for my daughter, age 20, who is not my dependant, can I deduct on my taxes?
No, You can only deduct tuition and fees deduction or education credits for yourself, your spouse and people listed as dependents on your return. Your daughter can claim the credit or deduction even if you pay the expenses.
I thought that if she was under 21 and enrolled in school full time and still lived at home that the parents can claim her. Maybe I'm mistaken.