A system like this was launched this year in Poland, this year limited to employees and contract workers, but it's planned to expand to self-employed / business

A system like this was launched this year in Poland, this year limited to employees and contract workers, but it's planned to expand to self-employed / business owners as well. If one doesn't log in / doesn't do anything, the form will be submitted Apr 30. If you log in you can update the form (e.g. add deductions or declare extra income), or just accept it as is - then it's submitted right away. There were some minor kinks, but in my opinion it was a success. Being self-employed I didn't get to use it, but saw how it works. I filed taxes on-line directly from my book keeping software and it took me ~20min, including getting my wife's pre-filled taxes from the govt service to combine with mine.