Originally Posted by
absoluy
If you're UuA on a fare originates from Europe (excl. UK) then you should only be paying ~$70 (primarily the difference in BA YQ surcharge) regardless of which direction you upgrade in (LHR-LAX or LAX-LHR). As long as you're transiting the UK for less than 24 hours you don't pay any UK APD at all.
If you're UuA on a fare that originates from the USA then you will pay significantly more cash when upgrading since the BA YQ amount for fares dept. the US is significantly higher than dept. Europe (e.g. LAX-OSL return in WTP has YQ of ~$300, OSL-LAX return has YQ of~$160 in WTP). When you upgrade that ticket departing LAX the YQ amount for a WTP to J upgrade goes from ~$300 to ~$600 so you end up paying ~$300+ for the upgrade vs. ~$70 if you were originating in Europe.
So it's not that the taxes are higher, it's that BA chooses to price base fares and YQ differently between Europe and US originating fares.
That's right in theory, but wrong in practice. OSL-LHR-LAX (Y + W as per cash purchase). If you UuA the LHR-LAX flight from W to J, BA more of than not will not be able to do the calculation properly. I suspect because it may be calculating 3 classes during the journey or maybe it's just bad programming. But I've had it where it will price the taxes for the LHR-LAX J flight including full UK APD, even with a 2 hour connection. I didn't argue the point as I actually got the J tier points in the end (also a common glitch apparently).