The whole point of this discussion introduced by the article linked at the top of the page is that electronic communication is only available to the general public for initial filing.

> the IRS offers free online filing to everyone

Not to dual-status individuals for example. Those individuals must mail/fax their return to IRS.

You are correct. For the tiny fraction of taxpayers who experience this once or twice in a lifetime event (dual status), they must paper file their split-year returns. I am sure there are some other extremely uncommon forms that are not supported as well.

Free Fillable Forms is run by "On-Line Taxes, Inc", not the IRS. It's not a direct service.

Thank you for the detail. It must be a sub-contractor to the IRS. The front page of the Free File Fillable Forms User Guide, however, is 100% branded as an IRS service, the online help is through the IRS web site[0], and the service is normally accessed initiallhy via the IRS web site, so you would only know about On-Line Taxes Inc. if you spent time reading, for example, the terms of service. For practical purposes, the taxpayer will see this as an IRS service, not a 3rd party. This is opposed to the Free File Alliance, where the taxpayer is only given a list of participating vendors and then is on their own.

[0]https://www.irs.gov/e-file-providers/free-file-fillable-form...