You’ve heard you can build a fourplex on a regular lot now.
The rules changed. Everyone got excited. But almost nobody explains how these deals actually work, or whether they’re right for you.
So here’s the honest version.
It’s a machine, and it runs in order
Missing middle is the housing between a single family home and an apartment tower. Fourplexes. Sixplexes. Stacked townhomes.
Building one isn’t really about the building. It’s a sequence, and each step decides the next.
The city sets what you’re allowed to build. Zoning is the rulebook that says how many units go on a lot, and it’s different in every city. Some now allow four, five, or six units where they used to allow one.
The lot narrows it. How wide it is, how deep it is, where the building can sit, where parking goes. Zoning gives you the maximum. The lot tells you what’s realistic. Those are rarely the same number.
The architect tells you the truth. They run your lot against the zoning and the building code and hand you your real options. And here’s what surprises people. You usually get a range, not an answer. A basement conversion, a duplex, a fourplex, or tearing it down for a six-plex. Same lot. Different projects.
Your capital picks from that range. The code says what’s allowed. Your money says what you can actually build. The real decision sits where those two overlap.
Most people pick the outcome they want first, then check the money. That’s backwards.
The unit count changes the rules
This is the part I want you to remember.
The number of units isn’t just a design choice. It decides which incentives you get.
Four units and up can qualify for the enhanced GST rebate on construction. That’s the government giving back the GST, or the federal part of the HST, you pay to build. It rose from 36% back to 100%, with no value cap. But there are rules. At least four self contained units, each with its own kitchen, bathroom, and living space. At least 90% held as long term rentals. And it’s for new supply, so renovating an existing house usually doesn’t count.
Five units and up puts CMHC’s MLI Select on the table too. That’s the program with the low down payment and long amortization everyone talks about.
There’s also a smaller tax perk. Normally you write off a rental building slowly, at 4% a year. For eligible new purpose-built rental, the government raised that to 10% a year, which came out of the 2024 federal budget. One honest note. That write off only brings your rental income down to zero, not below, so on a tight deal you may not use all of it.
The incentive that can matter most
Here’s one people miss, and it can be the biggest of all.
A development charge is a fee the city charges when you pull a building permit. In Toronto it can run $40,000 to $55,000 per unit, enough to sink a deal on its own.
The province now makes this easier everywhere. Across Ontario, the second and third units on a lot are exempt from development charges. That’s true in every city.
Some cities went further. In Toronto, development charges are now fully waived on projects up to six units. Just know that being allowed to build six units is separate from the waiver. You can build a fourplex on almost any Toronto residential lot without rezoning, but a sixplex is only allowed as-of-right in nine wards so far, with the city looking at expanding that. Other cities like Ottawa, Mississauga, Hamilton, and Vaughan have brought in their own cuts or waivers, each done differently, and some are temporary pilots with end dates.
Here’s the key point. This is a city by city thing, and it changes often. The same fourplex can cost tens of thousands more in one city than another. That’s why the city you choose comes first. It doesn’t just decide what you can build. It decides what it costs to build it.
The trap at the finish line
Now what almost nobody tells you.
You build it with expensive, short term construction money. You carry that, plus the land mortgage, for well over a year with no rent coming in. Not a dollar of income while interest, property tax, and insurance run.
Then you refinance into cheap, long, CMHC insured debt to pay off that expensive construction loan. Whatever’s left over comes back to you, ready for the next project.
That refinance is the whole point. But it doesn’t work the way people think.
CMHC doesn’t hand you money based on what the building is worth. They size the loan on whether the rent covers the mortgage payment, by a set margin.
So the appraisal sets the ceiling. The rent decides what you actually get.
Strong rents, you pull your capital out and go again. Soft rents, your money stays trapped in the building. It’s still your equity. You just can’t reach it.
You’re not betting on the build. You’re betting on the rent roll.
And then there’s tax
One more, and this one’s mine.
Here’s what trips people up. They think “I’m building to keep it and rent it out, so I’m not selling anything, so there’s no sales tax to worry about.”
That’s not how it works.
When you build a new rental and rent it out, CRA treats you as if you sold the building to yourself and bought it right back. It’s called the self-supply rule. On the day your first tenant moves in, you have to self-assess HST on the full value of the finished building. You never sold it, but the tax system acts like you did.
That’s actually why the GST rebate we talked about earlier exists. It gives you back the tax that this self-assessment creates. The two go together. You assess the tax, then you claim the rebate against it.
And if you build to sell instead of hold, it’s a different story again. CRA can treat you as a builder in business, so your profit is business income, fully taxed, with HST charged on the sale.
People assume real estate always means capital gains. It doesn’t. CRA looks at what you meant to do and what you actually did.
At some point, someone will pay tax. That is the general rule in Canada.
This part runs deep, so I’m giving it its own episode later in this series. The self-assessment, the rebate, the hold versus sell decision, and how to get the value right so you don’t hand CRA an easy audit. Keep an eye out for it.
So, is it your opportunity
The economics are lining up in a way they haven’t for a while. Softer prices, friendlier zoning, real incentives for holding rentals. That’s a genuine window.
But it isn’t for everyone. It takes real capital, real patience, and a year and a half or more of carrying costs before a dollar comes back. Done right, it builds serious wealth. Done wrong, it ties up your money and your nerves.
See how it works on a real project
This is the overview. The real education is in the details.
I sat down with Victoria Suen, a Toronto architect who helps her clients with these projects, and she walked me through what one actually looks like start to finish.
If you’re even a little curious about missing middle, watch that conversation next.
Next Steps
If you want to make sure your file can stand up to a second look, Book a consultation with my team today. We help everyday Canadians navigate the confusing world of taxes so you can keep more of what you earn.
Until next time, happy Canadian Real Estate Investing.
Cherry Chan, CPA, CA
Your Real Estate Accountant
