Owner-Built Home Rebate Calculator — GST191
If you're building on your own land, there's no builder to credit anything at closing: HST is assessed on the home's fair market value when it's substantially complete, and you claim it back yourself on form GST191. The best-known Ontario HST calculator explicitly excludes owner-built homes. This one is built for them — including the first-time buyer rebate.
Rules checked October 27, 2026 · Claim generally due within 2 years of substantial completion / occupancy.
How the owner-built claim works
An owner-built home is taxed differently from a builder purchase: instead of paying HST on a purchase price, you self-assess HST on the fair market value of the house and land when the home is substantially complete (90%+) or you move in, whichever the rules trigger first. Your claim then runs through form GST191 and its Ontario schedule. First-time builders with a start on or after March 20, 2025 can claim the same Bill C-4 + Ontario matching rebates as a builder purchase — at a $900,000 fair market value, that's the full $117,000. Repeat builders fall back to the standard New Housing Rebate (federally capped at $6,300 and phased out by $450,000; Ontario capped at $24,000), or the temporary enhanced window if the dates fit.
The cash-flow catch: there's no builder credit, so the HST is carried in full until CRA pays the GST191 claim. Budget for that gap. Buying from a builder instead? Use the GST/HST rebate calculator (GST190). Full picture: the stacking calculator.
Estimates only — not tax, legal or financial advice. Fair market value assessments are a common CRA review point; confirm your figures with CRA or your accountant before relying on them. Rules checked October 27, 2026.
Claim-ready worksheet — coming soon
We're building a printable worksheet that turns the numbers above into a claim-ready checklist: the right CRA forms, your deadlines, and the documents your lawyer will ask for. It isn't live yet, so this button deliberately does nothing.