If you are a registrant auctioneer selling goods for a person (who may be referred to as a vendor, owner or principal), you are considered to have made a sale of taxable goods. This means that whether the vendor is registered for GST/HST or not, it is you as the auctioneer who must charge and remit GST/HST on the sale of the vendor's goods. However, you do not charge or remit GST/HST on your commission or other services provided to the vendor that relate to the sale of the goods, such as storage and advertising.
Sometimes a registered vendor and an auctioneer make a joint election to have the vendor remit the GST/HST instead of the auctioneer. For more information, see Auctioneers' election.