Due to IRS adding new changes within the Schedules, there are now situations in which an upgrade may be needed. You are able to begin your tax return using TurboTax Free, but if you do not qualify for TurboTax Free, you will be prompted to upgrade.
Please see the following link for tax situations covered in TurboTax Free Edition.
https://ttlc.intuit.com/questions/1913043-is-turbotax-free-edition-right-for-me?jump_to=answer_3334660
If you don't qualify for TurboTax Free Edition, you may qualify for TurboTax Free File Program.
Here is more information on TurboTax Free File Program.
https://ttlc.intuit.com/replies/3301359
You can follow the instructions in the following FAQ to switch to the Free File Program.
https://ttlc.intuit.com/replies/3491786