I have not used CreditKarma's tax product, but I've heard folks say that it calculates some things incorrectly. I think that's understandable for a brand new product, but I'd be cautious about using it this year if you don't (1) have a very simple return, (2) check their work against the IRS forms/instructions and/or (3) check against another product.
(For those who don't want to give TurboTax or H&R money, I've been quite pleased with FreeTaxUSA, which is like $12 for federal and state. It's a bit less user friendly, but plenty good enough if you have some understanding of taxes, and there are way fewer upsells and overpriced crap.)
(For those who don't want to give TurboTax or H&R money, I've been quite pleased with FreeTaxUSA, which is like $12 for federal and state. It's a bit less user friendly, but plenty good enough if you have some understanding of taxes, and there are way fewer upsells and overpriced crap.)