Originally Posted by brp
My understanding is that this is basically a "luxury" tax for flying in a premium. Presumably you had already paid that, somewhere buried in your purchase taxes, for the J ticket. Then the upgrade to F wouldn't incur a tax.
That is correct, the tax is the same for J and F, so no additional tax for the upgrade. Only Y to J upgrades have to pay the tax. As an aside, the tax has existed for many years (at least 5) and AA paid it as a goodwill gesture -- until AA figured out that nobody realized that AA was giving them a gift of USD 40, and started to collect it. The rationale for the tax is that it pays for the cost of running the airport ground facilities used by premium pax; rather poor rationale, but that is how it is. Another irony of this tax is that Concorde was exempt from it -- being only 1 class, all F, there was no collection of taxes as all pax flew the
lowest class and not a premium class. Lots of lessons in that bit of history.