Sorry, but the .tax2018 tax file, is unreadable gibberish by itself.
And as already stated by others, the IRS cannot do anything at all with that datafile, nor can a tax lawyer/accountant/attorney unless that person happens to have 2018 TTX already installed on their own computer ( IF the file also contains a state file, you cannot open the data file without that state software installed too, even if you only need the Federal part.)
You'd need the 2018 software to open that datafile (along with the state software installed too...if the file includes any state) ...and then what shows up in the software is only printable as a PDF file. The full PDF file shows everything, and there would be an electronic filing page which would just show the last time you attempted to e-file. That's why I had suggested you just attempt to download the 2018 PDF file from your account (if your account allows you to do so)....that shows virtually everything that is in the datafile. (though I can imagine one or two exceptions)
Problem is, that you cannot get the 2018 software in a usable form: i.e updated to allow you to open that .tax2018 datafile if you don't already have it installed on your own computer (with a state(s) set too if one or more are in your file.)
And the 3rd party tax printer service (noted in one of the posts above) is your only option to open and print out what is in that 2018 datafile if you cannot download the PDF file from your account.
____________*Answers are correct to the best of my knowledge when posted, but should not be considered to be legal or official tax advice.*
