Flight School Booking's billing system integrates with the most popular bookkeeping packages. Configure the link at Admin > Billing > Bookkeeping.
The link to Xero, QuickBooks or Sage takes a lot of the work out of bookkeeping because the system keeps track of which transactions have been reported and which have not.
If you use another package, you can use the "Accounting summary report" under Billing > Reports, which provides the same information in a form you or your accountant can manually enter.