If I sell through an online marketplace like Amazon or Etsy, does the platform collect HST for me?

It depends on who you are and what you're selling. Rules aimed at digital platforms generally shift the responsibility to collect and remit GST/HST onto the platform itself mainly in specific situations, most notably where a non-resident vendor without a Canadian presence is selling through the platform, or where the platform is facilitating short-term accommodation bookings. If you're a Canadian-resident business selling your own goods through a marketplace, the platform generally does not automatically take over your HST collection obligations the way it might for a non-resident vendor using the same marketplace.

That means a Canadian seller who is, or should be, registered for GST/HST is typically still the one responsible for charging and remitting tax on their own sales made through the platform, even though the platform processes the payment and may show tax collected at checkout in some circumstances. Assuming the platform has it covered, without confirming how it applies to your specific seller status, can leave a real gap in your own compliance.

Because the platform rules distinguish carefully between different categories of seller and type of sale, and getting this wrong means you may be under-collecting tax you're actually responsible for, confirm your specific obligations with a tax advisor rather than relying on the marketplace's general checkout behaviour.