Need to upgrade HR Block 2017 tax software. I have a MacOS Big Spur. The tax software has an icon which has an prohibitory symbol over it indicating the program can't open in 32 bit form and needs to be upgraded to 64 bit by the developers.

They apparently don't know the trick to install an older OS.

1. Make sure the Mac is old enough to install the older OS. For High Sierra, you need a maximum of a 2017 Mac.
2. Use internet restore, command-option-shift-R to format and install the oldest OS on an external hard drive.
3. Then upgrade to 10.13 if it is older than 10.13 using these directions: https://discussions.apple.com/docs/DOC-12081

Contact H&R block to request the full installer link.

https://www.hrblock.com/support/

They may still require you to pay for the upgrade. A free federal return is possible with http://www.express1040.com/ and the state returns are usually less expensive. PayPal also offers tax return filing. However, neither imports data from HR Block's prior year returns digitally.