You are able to begin your tax return using TurboTax Free Edition, but if you do not qualify for it, you will be prompted to upgrade. 

Please see the following link for tax situations covered in TurboTax Free Edition.

Free Edition

To see what you are being charged for please follow the instructions in the following FAQ.

Review Fee's

In the regular Turbo Tax Free Edition, information that you can enter is limited now.  Why do I have to upgrade from the Free Edition?
https://ttlc.intuit.com/community/upgrading/help/why-do-i-have-to-upgrade-from-free-edition/00/26379

To go back to the Free Edition you can try to clear and start over https://ttlc.intuit.com/community/using-turbotax/help/how-do-i-clear-and-start-over-in-turbotax-onli...

OR There is also The Turbo Tax Free File program which is free for federal and state.  And has more forms than the Federal Free Edition, like Schedules A, B, C , D, E, F, EIC, H, K-1, SE,  etc.

To qualify for the Free File website  you just need to meet one of these 3 things
AGI $36,000 or less
Active duty military with AGI of $69,000 or less
OR qualify for EIC (earned income credit.)

In order to use the Free File program, you have to start it at a special website. Click on the Orange button I Qualify, Let's get Started
https://freefile.intuit.com/