Taxes and fees on reward flights

Afternoon all,

I have managed to secure a G fare SFO-LHR in April next year on the VS 20, however it seems that if you want to book a return the SFO to LHR leg is £168 in taxes and fees but if you book a one way SFO-LHR the fees are $457, is this normal?

Many thanks.

[buns]

Whilst I cannot comment on the difference, I do know that there are no credit card charges when flights originate from the US

buns