I collect HST/GST from only Canadian based CPA networks. But this is because my company is registered for HST/GST. When I invoice the Canadian company (Maxbounty for example is in Ontario) then I invoice my commissions plus tax. That Tax I hold till I have to send it to the government. I believe the cut off is $30K till you need to start charging tax. So if you do less than 30K a year it shouldnt matter. Obviously the best person to ask is your own accountant.