HST and Secondary Suites in a New Build in Ontario: What Buyers Should Know

Buying a new-construction home with a legal secondary suite — a basement apartment, a coach house, an in-law suite with its own entrance — is increasingly common in Ontario, and increasingly encouraged by municipal policy. It’s also a good example of how a feature that makes perfect sense on a floor plan can quietly complicate the HST and rebate side of your purchase.

If your new build includes a secondary suite you plan to rent out, don’t assume the HST and rebate picture works exactly the same as it would for a straightforward single-family purchase.

Why a Secondary Suite Changes the Picture

The GST/HST New Housing Rebate that many new-home buyers rely on is generally built around the idea that the buyer (or a close relation) will use the home as their primary residence. A secondary suite complicates that picture because part of the property — the suite itself — may be intended from the outset for a different use: an arm’s-length tenant, rather than the buyer or a family member.

Depending on how the suite is used, the property can end up being treated, in part, as a residential rental property rather than purely an owner-occupied home — and rental-use portions generally follow different HST and rebate rules than owner-occupied portions.

The Core Distinction: Owner-Occupied vs. Rental-Use Portion

If You’ll Live in the Main Unit and Rent the Suite to a Tenant

This is the scenario most likely to raise the question. The main unit may still qualify under the ordinary owner-occupancy rebate rules, while the secondary suite portion may need to be assessed separately — potentially under a different rebate regime aimed at new residential rental property, if one applies to your situation at all.

If a Relation Will Live in the Suite

Some rebate rules extend to a "relation" of the buyer using part of the property as their primary residence, which can be relevant if, say, a parent or adult child will occupy the secondary suite rather than an arm’s-length tenant. Whether this changes the analysis depends on the specific relationship and use — not something to assume without checking.

If You’ll Rent Out Both Units

Where neither unit will be occupied by the buyer or a qualifying relation, the owner-occupancy rebate generally doesn’t fit the fact pattern at all, and the analysis shifts toward rental-property rules from the outset.

Questions to Bring to Your Lawyer and Accountant

• [ ] Will you, or a qualifying relation, actually live in the main unit — or is the whole property intended for tenants?
• [ ] Is the secondary suite legally registered as a separate unit, and does that status affect how the builder has structured the sale and any rebate assignment?
• [ ] Has the builder’s purchase agreement addressed the suite specifically, or does it assume a single-family owner-occupied purchase?
• [ ] If part of the rebate doesn’t apply because of the rental portion, how does that affect the price you actually pay at closing?

Why This Article Doesn’t Quote Rebate Figures

The dollar amounts and eligibility mechanics for new-home HST/GST rebates — including how they interact with a secondary suite or rental portion — are genuinely technical and, as of mid-2026, are also affected by multiple overlapping federal and provincial programs that are still being finalized in some respects. Rather than state a number that may not hold up, this article describes the general shape of the issue and points you toward the professionals who can confirm current figures against your specific floor plan and intended use.

Frequently asked questions