Mississauga · for landlords
Registering a second unit in Mississauga costs nothing. Not registering is visible to anyone who looks, because the City publishes the registry and tells people to check it before reporting an illegal unit.
The City's definition: a self-contained living space with cooking, sleeping and sanitary facilities, inside a detached house, semi-detached house or townhouse. Basement apartment, in-law suite, accessory dwelling — same thing under three names.
The practical test is the kitchen. A rented room that shares your kitchen is not a second unit; it is a room, and a different set of rules applies to it. A basement with its own kitchen, bathroom and sleeping area is a second unit and this page is about it.
The City says all second units must meet the Ontario Building Code, the Ontario Fire Code and Zoning By-law requirements, and be registered under the Second Units Registration By-law. Registration is the paperwork at the end; it is not a substitute for the unit actually being compliant.
No fee. You may still pay for a building permit, fire inspection, design work or the renovation itself — but not for the registration.
Documents go to secondunits@mississauga.ca. No portal, no appointment.
Registered units appear on the Second Units Registry List, updated in the second week of every month.
The City's own instructions for reporting an illegal second unit are: check the Second Units Registry List first, and if the unit is not on it, call 311.
So the consequence of not registering is not an inspector happening to notice. It is that a neighbour, a disgruntled former tenant, or anyone who has ever been annoyed about parking can confirm your unit is unregistered in under a minute and report it with one phone call. That is a much shorter path to a problem than most owners assume.
If you don't have a signed-off permit, that is the real job and the registration waits behind it. Start there rather than with the form.
A self-contained living space with cooking, sleeping and sanitary facilities, inside a detached house, semi-detached house or townhouse. If it has its own kitchen, sleeping area and bathroom, it is a second unit.
Yes. The City states that all second units must meet the Ontario Building Code, the Ontario Fire Code and Zoning By-law requirements, and must be registered under the Second Units Registration By-law.
There is no fee to register. You may still pay for a building permit, fire inspection fees, professional design work or renovation costs, but the registration itself is free.
Yes. Registered units go on the Second Units Registry List, which the City updates in the second week of every month. The City tells anyone reporting an illegal unit to check that list first and call 311 if it is not there.
Email proof of ownership, a signed-off second unit building permit and a completed Second Unit Registration Form to secondunits@mississauga.ca.
This is general information, not legal advice, and we are not the City. Everything here was read directly from the City of Mississauga's Registering a second unit page on 11 September 2026. Rules change — check that page before relying on any of this, and email secondunits@mississauga.ca or call 311 for anything specific to your property.
Registration is the slow, administrative half. Advertising is the half people put off, because writing the ad means deciding what to charge and describing the place. We built RoomFinderAI to remove that: add one photo and it drafts the title, the rent and the description, and you correct what it got wrong. What belongs in the written agreement and the equivalent rules in Brampton are written up separately.
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