QuickBooks Premier and Enterprise for Accountant versions only have the capability to convert an Accountant's Copy transfer file (.QBX) to a working file. Other versions don't have this option. That's the reason why you can't see it from the File menu.
The Accountant's Copy uses the Dividing Date to define the fiscal period the accountant can work on. While you can't import/convert the .QBX file, you can import the accountant's changes (.QBY). Please follow the steps found in this article: Import accountant's changes.
I'll share with you an article about how to use the Accountant's Copy. Please check it out: https://quickbooks.intuit.com/community/Reports-and-accounting/Use-the-Accountant-s-Copy/m-p/203725.
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