How Is the GST/HST New Housing Rebate Calculated on a Home Priced Between $350,000 and $450,000 in Canada?

This answer covers Canadian federal tax law, which applies in every province.

On a builder purchase priced between $350,000 and $450,000, the rebate is A × [($450,000 − B) ÷ $100,000], where A is the lesser of $6,300 and 36% of the tax paid and B is the total consideration. At $450,000 or more it is nil. At $350,000 or less, you get the full A amount.

For example, with 5% GST paid on a $400,000 home, A is capped at $6,300 because 36% of $20,000 is $7,200, so the rebate is $6,300 × ($450,000 − $400,000) ÷ $100,000, or $3,150. The rebate is a percentage of tax paid, not of price, capped at $6,300 at 5% GST or 13%, 14% or 15% HST.

For a builder purchase, the thresholds are tested against total consideration, which is the purchase price excluding GST/HST and certain other amounts. Owner-built homes use fair market value instead, with B being the greater of $350,000 and that value. At or above $450,000, only the first-time home buyer rebate may help, if you qualify. A lawyer or accountant can confirm your numbers.