TurboTax does not charge a percentage. TurboTax has set prices for the product fees.
If you are using a paid edition, TurboTax even charges a preparation fee if someone has no refund at all and has to pay additional Federal tax due.
If you are using Online Deluxe (that's what is shown by your screen name above), the Federal return is currently 39.99, and the State return is 36.99. (Be aware that those prices will rise after 2/28, if the discounted price is not locked in before then by either filing or paying in advance.)
If you choose top pay the TurboTax fees out of the Federal refund, there is an additional 39.99 service fee for that option (44.99 for California filers, where it is bundled with Premium Services.) If you chose that payment method and wish to remove it prior to filing, we can tell you the proper way to do so and how to then pay your fees upfront with credit/debit card or a prepaid debit card you can buy in a store.
