Still not certain how Airbnb will handle this. But here's an official response from Ministry of Finance addressing "transition"
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CTBTaxQuestions@gov.bc.ca
Thank you for your reply and follow-up inquiry.
Our understanding is that you are concerned with accommodation booked prior to October 1, 2018, but not provided until after that date. Otherwise, there is no change in the application of the PST.
Information on the “transitional rules” relating to accommodation, as of October 1, 2018, are found on page 3 of Notice 2018-004, Notice to Accommodation Providers, with examples.
The date a “confirmation” for the booking for accommodation is issued (including the acceptance of a deposit) does not determine whether the old (current) or new rules apply. Please note, however, that deposits are not subject to PST. The PST becomes payable when a deposit is applied against the purchase of a room.
If the guest has already booked a stay (before October 1, 2018) for some time after the date when the new rules come into effect, in almost all cases the new rules will apply – that is, they will need to pay the 8% PST (plus the up to 3% MRDT, if applicable).
For the most part, the current rules (i.e., no requirement to collect PST if offering three or fewer units of accommodation) would apply only if the room was paid in full before October 1, 2018. This would include a case where the accommodation provider has a “no-cancellation” policy, or a policy that the purchase price will be charged unless the cancellation occurs before a particular date (this is considered to constitute a purchase of accommodation, even though it is not actually used), and the purchase price for the accommodation is charged under those policies prior to October 1, 2018.
This correspondence describes how the Ministry interprets the relevant tax provisions for information purposes only. This response may be impacted by variations in circumstance, subsequent changes to legislation or subsequent court decisions. The Ministry is not responsible for updating this response if there are any subsequent changes to the law. This response is provided as an aid to understanding the legislation and is not intended to replace the legislation.
Rulings and Interpretations Team
Ministry of Finance
www.gov.bc.ca/consumertaxes