@Fiat Lux - ASIA 

Thank you for reaching out.  However, I am a bit confused.  We currently have and were running QB Desktop 2015 for Mac on her computer,.  That computer -- the only Mac in the shop -- has just been upgraded to the Big Sur OS.  Because of the upgrade, QB 2015 Mac no longer opens the file.  Are you saying that:

• A newly downloaded trial version of QB 2015 Mac will run on a Mac desktop with Big Sur OSand will open the file? 

Or..

• A downloaded trial version of QB 2015 Windows will import the Mac file in native format, and I could do my closing the books with that program?

Regardless, thank you for any insights that you can provide.