When an order has been filled (either partially or completely), TWS automatically delivers execution and commissions reports via the execDetails and commissionReport events from the EWrapper interface. These events will usually be accompanied by a commissions report as long as the order was placed by the connected client application and/or the client application is connected with the master client ID.
This information can also be received after the trade was executed for as long as 24 hours from the order’s fill using the reqExecutions method. This method passes an ExecutionFilter object, which allows you to further refine the query. Leaving all fields of this object blank will retrieve all available execution reports.
In IBSampleApp, you can request execution reports on the Trading tab: