According to my findings from the web, the new HST will be applied to only new constructions of $400K or more. In the old system, each new construction is subject to the 5% GST which is already covered in builder's listing price. When HST will be introduced next July, an additional 8% tax will be required of each house. But at the same time, customers will get a 75% rebate of the 8% tax they paid. The net effect is about 0.75*0.08 or 2% additional tax to be paid on the full price of the house after July 1.