https://bugs.winehq.org/show_bug.cgi?id=50011
--- Comment #8 from Joerg Schiermeier mywine@schiermeier-it.de --- Sorry Austin: I was wrong.
This software still exists and is offered from its official download location here: https://www.elster.de/eportal/infoseite/download_elsterformular There are three versions: -a small one for personal tax declarations -a medium installation for small businesses and self-employed taxpayers -a complete installation with all forms for any kind of company
The update connection is still working. And also the interface connector for uploading the tax data should work.