How do I open .tax2021 files if I do not have the desktop software for it anymore?

Either reinstall the 2021 program 

OR you could try the TaxPrinter service to convert a .tax file to pdf at
https://www.taxprinter.com

They might be expensive and it is probably not safe to email tax returns back and forth. They are not related to Turbo Tax. I see it says federal is $44.99 and Federal + state is $79.99.

You can buy 2021 program again here,

https://turbotax.intuit.com/personal-taxes/past-years-products

If you still have the 2022 desktop software, it will open a 2021 tax file - of course presenting it as 2022 tax data (importing 2021 data to the 2022 software). So it depends on why you want to open this tax file.

Thank you!

Thank you