Originally Posted by
avarnathan
Thanks for your suggestion. The $450.00 is because the connecting flight is via LHR and the tax is high.
In all likelihood, the reason for the $450 charge is not a high tax and not exactly that the connecting flight is via LHR. It's that BA imposes hefty surcharges on award flights on its planes even if you book your award through a partner. AA does not imposes surcharges on its own flights, and other partners, such as IB, have lower surcharges.