Michel, I'm not an expert on Canadian tax, but surely you can establish an independent subsidiary that provides service to Canadians or anybody else that wants to pay tax. That company then contracts for service from UT, paying you a monthly/annual/whatever fee for the service. That fee would have tax added but you'd offset that against the tax paid by the Canadian subscribers.
"... They ne'er cared for us
yet: suffer us to famish, and their store-houses
crammed with grain; make edicts for usury, to
support usurers; repeal daily any wholesome act
established against the rich, and provide more
piercing statutes daily, to chain up and restrain
the poor. If the wars eat us not up, they will; and
there's all the love they bear us."
-- Shakespeare: Coriolanus, Act 1, scene 1
