I can take it out of S mode but cannot go back if I do. I'm wondering if there is a way to load non-verifiable programs. I've checked the Microsoft store and they don't have TT software in the store. They do have a TT view app, but I don't know if this will help me. For you info, I bought my 2018 TT premier fed and state from Amazon in Jan 2019.
I can take it out of S mode but cannot go back if I do.
Why on earth would you ever want to go back to S-mode? In my opinion, S-Mode should be called C-mode, where C stands for "Crippled".
Bottom line is, if you want to install TurboTax or any other third party app not purchased from the Windows Store, then you flat out can not so long as you remain in S-Mode.
It is not like a Chromebook but it may not be a full windows version. If I switch out of S mode, I can't return to it. Is there a way that Windows 10-S allows non-verifiable apps/programs to be loaded?
Is there a way that Windows 10-S allows non-verifiable apps/programs to be loaded?
No, in S mode there is no way to install an app that is not from the Microsoft Store. Essentially, when you bought your new computer with Windows 10 S you agreed to accept the limitation that you could only use apps from the Microsoft Store unless you permanently switch it out of S mode.
But this is a Windows question, not a TurboTax question. You should ask in a Windows support forum. TurboTax does not determine what Windows 10 S allows or does not allow.
There's no charge to switch out of S mode. On your PC running Windows 10 in S mode, open Settings > Update & Security > Activation. In the Switch to Windows 10 Home or Switch to Windows 10 Pro section, select Go to the Store. On the Switch out of S mode (or similar) page that appears in the Microsoft Store, select the Get button.
i can not tell you if there will be a charge for upgrading win 10-S but unless you do only apps from MS store can be installed.