What changed in 2022.
Before Bill 23, most Ontario residential lots were zoned for a single dwelling. Adding a second or third unit usually required a zoning amendment (a public process, 6–18 months) and full development charges (often $20,000–$40,000+ per unit, depending on the municipality).
Bill 23 (the More Homes Built Faster Act, royal assent November 2022) overrides those local rules for up to three units per residential lot. The change is 'as of right' — you apply for a building permit, not a zoning amendment. Public hearings aren't required. Development charges are eliminated for qualifying secondary units.
The 3-unit-as-of-right rule.
Most residential lots in Ontario can now have three units of any combination: the main house plus two secondary units (a basement apartment + a garden suite, for example), or one secondary unit plus a duplex configuration of the main house.
The rule applies to lots zoned for residential use across the province — including Hamilton, Burlington, Oakville, Toronto, and most of southern Ontario. There are edge cases (heritage districts, certain conservation areas, lots smaller than a municipality's minimum) where additional approvals may apply. We check this at the walkthrough.
Dev charges eliminated — for qualifying ADUs.
Development charges are the per-unit fee municipalities use to fund infrastructure (water, roads, schools). Pre–Bill 23, these were a major cost line for a garden suite project — often more than the foundation itself.
Bill 23 eliminates dev charges for qualifying additional residential units. "Qualifying" generally means the unit is part of an existing residential lot, under the size cap, and meets the secondary-unit definition. Some municipalities still charge limited fees (planning fees, building permit fees) but the big DC line is gone.
Exact eligibility for the DC exemption varies by municipality. We track the latest position with each city we work in.
Parking requirements dropped to zero.
Pre–Bill 23, most Ontario municipalities required at least one parking space per additional unit. On smaller lots this often killed projects — the parking footprint left no room for the unit itself.
Under Bill 23, the minimum parking requirement for additional residential units is zero. You can still provide parking if you want to; you just don't have to.
Max sizes — vary by municipality.
Bill 23 doesn't set a single province-wide maximum size for ADUs. Each municipality sets its own cap within its zoning bylaw. Hamilton, for example, currently caps detached garden suites at 75m² gross floor area. Other cities are higher or lower.
Burlington, Oakville, and the GTA each have their own current cap. Toronto has a dedicated laneway suite framework that interacts with Bill 23 differently. We confirm your city's current cap at the walkthrough and design within it.
Eligibility — most lots qualify.
Most residential lots in Ontario qualify for at least one additional unit under Bill 23. To know what specifically your lot allows we check: lot size, current zoning (R1, R2, R3, etc.), setbacks (from main house, side lot lines, rear lot line), services (water, sewer, electrical capacity), heritage status (if applicable), and conservation authority status (if your lot is near a regulated area).
Edge cases that need extra review: small infill lots (less than the municipal minimum), heritage-designated properties, lots in conservation regulation areas, and lots without adequate servicing. We flag these on day one of the walkthrough.
Permit timeline — what to expect.
An ADU permit under Bill 23 follows the standard building-permit process — not the zoning-amendment process. That's the speed gain: weeks instead of months.
Typical timelines: Hamilton 8–14 weeks from complete application. Burlington 10–14 weeks. Oakville 10–16 weeks. Toronto 12–20 weeks for laneway suites. These are city-side review times — we file complete applications first time to avoid resubmission delays.
Tax + income implications.
An additional unit affects property tax (the lot's MPAC assessment goes up) and may affect HST treatment of construction (rental units have different rules than owner-occupied secondary units). If you rent the unit, rental income is taxable.
We're not tax advisors. We can refer you to accountants who specialize in residential real estate if you want a tax model before committing. The walkthrough doesn't cost anything; getting the tax picture right before signing is on you.