Can I open a .tax2021 turbotax home and business file with a 2021 turbo tax premier software or 2121 turbotax deluxe software?

[VolvoGirl]

Yes.  All the Desktop programs have the same forms.  You just get more help in the higher versions.  

Do you need to install a 2021 program?  

After you get the program installed or reinstalled the first thing to do before you open your tax return is to update the program and install any state programs you had. Then open your file. So you first might need to start a fake return to be able to download the state program (go to FILE - NEW). Enter some basic information, then go to the state tab and download the state program. Then try to open your existing return, go to FILE - OPEN