I tried to use Credit Karma last year for my daughter. I think it would not do the form needed to pay taxes on her scholarship (8515?) for free. She’s now got an account with them and I do get her credit reports because I used my email to try to do the taxes.
Two years ago I ended up using TaxAct for one, TT for one, and TaxAmerica? (something like that) because of the forms each would provide for free. I think I was in the wrong TT online for the free ones. Then last year I figured it out because of a tip on CC. This year the only issue was logging in but now everything is good on turbotax.