1. reporting scholarship income (goes on the line beside box 1 and nowhere else), and 2. state taxes are not supported, and my state does not have an equivalent service.
An example is figuring out whether I would owe taxes on the gain from the sale of a primary residence I owned for less than 2 years. Figuring that out manually took some googling, finding an IRS guide, reading multiple pages of regulations along with exceptions and determining where I stood.
Another is determining HSA contribution limits when my wife and I were in individual HDHP plans part of the year, and a family plan the remainder.
0: https://www.irs.gov/filing/free-file-do-your-federal-taxes-f...
The whole thing is a mess because TurboTax and H&R Block and the like want to stay in business. If the process is too easy then the middlemen won't survive.
(State taxes are a different matter; I've paid Illinois and Michigan taxes recently, and they do provide an easy and obvious way to e-file directly with the state.)
There are no income exclusions or anything. It is possible you will be unable to use it if you have to use some really obscure forms, but it does have all the forms that paid Turbo Tax can file for you. You also might not be able to use it if you have one of those weird tax situations where the IRS instructs you to write a message across the top of your 1040.
https://www.irs.gov/e-file-providers/free-file-fillable-form...
It’s all electronic. You get an email confirmation.