Thanks for reaching out to the Community. I'm here to provide clarification on upgrading your accountant's copy.
If an accountant makes changes using features that aren't available in the client's version of QuickBooks Desktop, changes will not import to the client's file. This is why you'll need to upgrade your file when you open an Accountant's Copy in a newer version of QBDT.
However, you can still work on the Accountant's Copy using a different version as long as the gap between the versions is just one year, and the accountant has a more recent version. For more information about using the accountant's copy, you can check out this detailed article: Use the Accountant's Copy.
Feel free to comment below if you have any more questions. I'm always here to lend a hand and help. Take care!
The client upgraded QB 2017 to QB 2020 directly through QuickBooks. Now the client can't import the changes to the QB17 file because QB17 is no longer on the computer. If the client opens the company file in QB20, can the change file (which is in 17) still be imported?