Originally Posted by
stargold
Probably an obvious answer for many, but for a Y-J upgrade, do I need to pay any additional surcharge associated with a J ticket, or is miles the only required payment?
It depends on the route. In most cases the answer is no, it's miles only. However, UK departures have to pay an extra £78 GBP (increasing to £84 in April) in Air Passenger Duty and I believe there are another one or two countries where some sort of charge is also applied.