Accounting service will do it automatically while closing the accounting period within the application. Application will remind you about this - please make sure that you can receive push messages from Aion.
If you would like to pass the extra files to your accountant (not invoices from My Invoices or expenses from My Expenses), then you can send them to the accountant using the accounting support. Open My Accountant, click settings icon on the upper right corner, select "Accounting Support" and then "Correspondence" tab. Here you can send the message with attachment to the accountant.