Do I owe HST if I switch my long-term rental condo to short-term Airbnb use?

Potentially, yes. Long-term residential rentals are generally exempt from GST/HST, while short-term accommodation, commonly understood as rentals of less than a set number of consecutive days to the same person, is generally treated as a taxable supply. Switching a condo from a long-term tenancy to short-term Airbnb-style stays can therefore be treated as a change in use from an exempt activity to a taxable one, which can trigger a self-assessment obligation on the property under the Excise Tax Act's change-of-use rules, separate from the ongoing question of whether you now need to charge and remit HST on the nightly bookings themselves going forward.

This catches owners off guard because the switch feels like the same physical property doing the same basic thing, housing guests, when in fact the tax character of the activity has changed. Once operating as a short-term rental, you may also need to register for and charge HST on your booking revenue if your activity is no longer a small supplier, on top of any one-time change-of-use consequences on the property itself.

Because both the one-time change-of-use assessment and the ongoing registration and collection obligations can apply, get this reviewed with an advisor before converting a long-term rental to short-term use, not after guests start booking.