In case I am using the NARF program to sell on Amazon Canada with my stock based in the USA but showing in Canada too, and a customer from Canada buys from me, am I still responsible for paying GST in Canada?
As far I know Amazon handles the whole stuff. And you are remote fulfilling that customer.
Same like he/she would buy from you and you send the goods by post to Canada. You wouldn’t need to pay nothing there just in your own country.
No, only if your sales increase from 30k in year.