The 'taxes' are effectively just the user fees. Each time you reissue, the system will recalculate the appropriate fees for the itinerary and levy them.

Sales taxes, transportation taxes, etc. are generally levied only in the country where the ticket is issued. This can be a way of saving money on taxes.

For example, if I buy a YYZ-HKG, but I have it ticketed here in NYC, I do NOT pay GST or Canadian Transportation Tax on the tkt, even though the point of origin is YYZ. Since the sale takes place outside of Canada, it is not leviable. Similarly, since the tkt does not originate in the USA, I do not pay US transportation taxes or segment charges.

(It is a cute trick I discovered when AC was selling seat sales on YYZ-HKG, but not NYC-HKG).

When I move to YVR in the summer, I think I may find a travel agent in Bellingham with whom to do business!