Farms are mixed-use properties. The farm house and surrounding immediate acreage (sometimes considered to be two acres) can be considered to be a principal residence, which would be exempt from HST. The rest of the land would be used in a business, on which payment of HST may be required. A Seller need not collect HST on the sale if the Buyer is registered for HST and undertakes to self-assess, report, and remit any HST accordingly.