only years you can now file if you are due a refund are 2017-2019. refunds for any earlier years are lost.
if you owe for prior years the IRS can come after you forever.
returns using TT app for 2017-2019 can only be prepared with its desktop software - MAC or WINDOWS - no cell phones
https://turbotax.intuit.com/personal-taxes/past-years-products/
