The 20% Down Payment Rule Is a Calculation, Not a Finish Line
A couple walked into my office last month with $130,000 saved and an $850,000 condo in mind. They'd done the math: 15% down was $127,500, which left them breathing room. Twenty percent was $170,000, which they couldn't reach without help. The mortgage broker had suggested they borrow from family to hit the threshold and "avoid throwing money away on insurance." The insurance premium they'd be avoiding: $16,500, added to the mortgage. The cash they'd need to borrow to avoid it: $40,000.
I walked them through the actual monthly difference. At 15% down with a 4.5% rate, their payment would be roughly $4,680. At 20%, it would be $4,524. The savings: $156 a month. The cost to generate that savings: draining every dollar they had, plus taking on a family loan with its own emotional and financial strings.
They went with 15%. They kept the liquidity. The insurance premium gets added to the principal and amortized over the life of the mortgage, which means they'll pay interest on it, call it an extra $24,000 over 25 years if they never refinance or pay it down early. But they have $40,000 in a high-interest savings account earning 4.8%, they covered closing costs without scrambling, and they're sleeping fine.
Where the 20% target actually works
The threshold isn't arbitrary. Mortgage default insurance exists because lenders won't take uninsured risk on high-ratio loans, and the government backstop (through CMHC, Sagen, or Canada Guaranty) comes with a fee. That fee scales down as your down payment increases: at 5% down, the premium is roughly 4% of the mortgage amount. At 10%, it drops to 3.1%. At 15%, it's 2.8%. At 19.99%, you're still paying it. At 20%, it disappears.
For a buyer with $160,000 saved on an $800,000 purchase, putting down exactly 20% saves $17,920 in premiums and cuts the monthly payment by about $295. If that buyer has another $15,000 set aside for closing costs and an emergency fund that won't be touched, the move makes sense. The insurance cost is real, the monthly relief is meaningful, and the liquidity position doesn't collapse.
The threshold also becomes non-negotiable above $1 million. OSFI rules prohibit insured mortgages on homes over that price, which means 20% isn't a choice, it's the minimum to qualify. For Toronto and Vancouver buyers, that turns the calculation into a gate, not an optimization.
Where it breaks
The problem shows up when hitting 20% requires liquidating everything. I've seen buyers pull from TFSAs, delay RRSP contributions, borrow from retirement accounts, and even take on side debt to avoid the insurance premium. The logic: "We're saving $15,000 in premiums, so it's worth it."
But $15,000 saved on the mortgage isn't $15,000 in your account today. It's $15,000 you're not borrowing, amortized over decades. If getting there means you have $3,000 left after closing instead of $35,000, you've traded a long-term cost for a short-term fragility that can break you in six months if the furnace dies or you lose a job.
The other miss: insured mortgages often qualify for better rates. In mid-2026, the spread between insured and uninsured rates sits around 0.25% to 0.35%, with insured borrowers getting the edge. A buyer choosing 15% down at 4.4% versus 20% down at 4.65% can end up with a lower effective cost even after paying the insurance premium, depending on how long they hold the term.
The actual test
Run the numbers with three variables: the premium saved, the monthly payment change, and the cash left after closing. If hitting 20% saves you $12,000 in premiums, drops your payment by $200, and still leaves you with six months of expenses in liquid reserves, do it. If it saves $18,000 but leaves you with two months of reserves and no margin for error, you're optimizing the wrong variable.
The threshold is a lever, not a finish line. Use it when the math and the liquidity both work. Otherwise, pay the premium, keep the cash, and sleep.
A couple walked into my office last month with $130,000 saved and an $850,000 condo in mind. They'd done the math: 15% down was $127,500, which left them breathing room. Twenty percent was $170,000, which they couldn't reach without help. The mortgage broker had suggested they borrow from family to hit the threshold and "avoid throwing money away on insurance." The insurance premium they'd be avoiding: $16,500, added to the mortgage. The cash they'd need to borrow to avoid it: $40,000.
I walked them through the actual monthly difference. At 15% down with a 4.5% rate, their payment would be roughly $4,680. At 20%, it would be $4,524. The savings: $156 a month. The cost to generate that savings: draining every dollar they had, plus taking on a family loan with its own emotional and financial strings.
They went with 15%. They kept the liquidity. The insurance premium gets added to the principal and amortized over the life of the mortgage, which means they'll pay interest on it, call it an extra $24,000 over 25 years if they never refinance or pay it down early. But they have $40,000 in a high-interest savings account earning 4.8%, they covered closing costs without scrambling, and they're sleeping fine.
Where the 20% target actually works
The threshold isn't arbitrary. Mortgage default insurance exists because lenders won't take uninsured risk on high-ratio loans, and the government backstop (through CMHC, Sagen, or Canada Guaranty) comes with a fee. That fee scales down as your down payment increases: at 5% down, the premium is roughly 4% of the mortgage amount. At 10%, it drops to 3.1%. At 15%, it's 2.8%. At 19.99%, you're still paying it. At 20%, it disappears.
For a buyer with $160,000 saved on an $800,000 purchase, putting down exactly 20% saves $17,920 in premiums and cuts the monthly payment by about $295. If that buyer has another $15,000 set aside for closing costs and an emergency fund that won't be touched, the move makes sense. The insurance cost is real, the monthly relief is meaningful, and the liquidity position doesn't collapse.
The threshold also becomes non-negotiable above $1 million. OSFI rules prohibit insured mortgages on homes over that price, which means 20% isn't a choice, it's the minimum to qualify. For Toronto and Vancouver buyers, that turns the calculation into a gate, not an optimization.
Where it breaks
The problem shows up when hitting 20% requires liquidating everything. I've seen buyers pull from TFSAs, delay RRSP contributions, borrow from retirement accounts, and even take on side debt to avoid the insurance premium. The logic: "We're saving $15,000 in premiums, so it's worth it."
But $15,000 saved on the mortgage isn't $15,000 in your account today. It's $15,000 you're not borrowing, amortized over decades. If getting there means you have $3,000 left after closing instead of $35,000, you've traded a long-term cost for a short-term fragility that can break you in six months if the furnace dies or you lose a job.
The other miss: insured mortgages often qualify for better rates. In mid-2026, the spread between insured and uninsured rates sits around 0.25% to 0.35%, with insured borrowers getting the edge. A buyer choosing 15% down at 4.4% versus 20% down at 4.65% can end up with a lower effective cost even after paying the insurance premium, depending on how long they hold the term.
The actual test
Run the numbers with three variables: the premium saved, the monthly payment change, and the cash left after closing. If hitting 20% saves you $12,000 in premiums, drops your payment by $200, and still leaves you with six months of expenses in liquid reserves, do it. If it saves $18,000 but leaves you with two months of reserves and no margin for error, you're optimizing the wrong variable.
The threshold is a lever, not a finish line. Use it when the math and the liquidity both work. Otherwise, pay the premium, keep the cash, and sleep.
Read Next
How Dual Citizens Can Claim RESP Tax Benefits Without Form 3520 Reporting
Bond Markets Are Pricing In Recovery, Not the 1970s Replay Already Underway
Why Fortress Tells Private Credit Lenders to Stop Chasing AI Data Centre Deals
Canada's Tax Code Punishes Work and Rewards Wealth Hoarding: Four Reforms That Would Actually Fix It