Why a 15% Down Payment Gets You a Lower Rate Than 25%
The federal government guarantees every mortgage where the borrower puts down less than 20%. That guarantee changes how lenders price the loan.
A mortgage with 15% down must be insured by CMHC, Sagen, or Canada Guaranty. The insurance protects the lender, not the borrower. If you default, the insurer covers the loss. From the bank's perspective, the loan carries zero default risk. The borrower still loses the house. The bank does not lose the money.
A mortgage with 25% down is uninsured. There is no external party absorbing the loss if the loan goes bad. The bank holds that risk on its own balance sheet, and OSFI requires it to set aside more capital against uninsured mortgages than insured ones. More capital held in reserve means higher cost to the lender.
That cost difference flows directly into the rate you are offered. As of mid-2026, the spread between an insured mortgage (on high-ratio loans under 20% down) and an uninsured one (on conventional loans at 20% or more down) sits between 0.30% and 0.55%. The borrower with more equity pays more to borrow.
The funding advantage
Lenders bundle insured mortgages into National Housing Act Mortgage-Backed Securities and sell them to investors. Because these securities carry a government guarantee, they trade at yields close to government bonds. This gives the lender access to cheaper funding than it can get for uninsured loans, which must be funded through deposits or unsecured borrowing.
The lender passes along its lower cost of capital to the borrower with 15% down. The loan is easier to securitize, cheaper to fund, and safer to hold. The rate reflects that.
The premium you pay upfront
The lower rate comes with a mandatory insurance premium. At 15% down, CMHC charges 2.80% of the total mortgage amount in 2026. That premium gets added to your principal, and you pay interest on it for the life of the loan.
On a $500,000 mortgage, the premium is $14,000. If you amortize that cost over a five-year term at 4%, the effective increase to your borrowing cost is roughly 0.28% annually. A 25% down buyer pays a rate 0.30% to 0.55% higher but skips the premium. Over five years, the math is close. Over ten, the premium often costs more than the rate discount saves.
The $1.5 million ceiling
Mortgage insurance is capped at homes priced up to $1.5 million. A buyer in Toronto with $140,000 down on a $1,499,000 home qualifies for the insured rate. A buyer with $305,000 down on a $1,525,000 home does not, even though they have more equity. The system creates a rate cliff at the insurance limit. The buyer just above the cap faces a higher rate despite putting more money in.
Why the system exists
The structure is not accidental. Canadian banking law prohibits federally regulated lenders from issuing a mortgage above 80% loan-to-value unless it is insured. The policy shifts housing market risk from the private sector to the government. During downturns, banks continue lending to first-time buyers because the loans are guaranteed. The tradeoff is that buyers with less equity get better pricing than buyers with more.
A 25% down payment signals stronger finances to most people. To a lender's balance sheet, it signals higher capital requirements and no external guarantee. The rate reflects what the loan costs the bank to carry, not what it says about you.
The federal government guarantees every mortgage where the borrower puts down less than 20%. That guarantee changes how lenders price the loan.
A mortgage with 15% down must be insured by CMHC, Sagen, or Canada Guaranty. The insurance protects the lender, not the borrower. If you default, the insurer covers the loss. From the bank's perspective, the loan carries zero default risk. The borrower still loses the house. The bank does not lose the money.
A mortgage with 25% down is uninsured. There is no external party absorbing the loss if the loan goes bad. The bank holds that risk on its own balance sheet, and OSFI requires it to set aside more capital against uninsured mortgages than insured ones. More capital held in reserve means higher cost to the lender.
That cost difference flows directly into the rate you are offered. As of mid-2026, the spread between an insured mortgage (on high-ratio loans under 20% down) and an uninsured one (on conventional loans at 20% or more down) sits between 0.30% and 0.55%. The borrower with more equity pays more to borrow.
The funding advantage
Lenders bundle insured mortgages into National Housing Act Mortgage-Backed Securities and sell them to investors. Because these securities carry a government guarantee, they trade at yields close to government bonds. This gives the lender access to cheaper funding than it can get for uninsured loans, which must be funded through deposits or unsecured borrowing.
The lender passes along its lower cost of capital to the borrower with 15% down. The loan is easier to securitize, cheaper to fund, and safer to hold. The rate reflects that.
The premium you pay upfront
The lower rate comes with a mandatory insurance premium. At 15% down, CMHC charges 2.80% of the total mortgage amount in 2026. That premium gets added to your principal, and you pay interest on it for the life of the loan.
On a $500,000 mortgage, the premium is $14,000. If you amortize that cost over a five-year term at 4%, the effective increase to your borrowing cost is roughly 0.28% annually. A 25% down buyer pays a rate 0.30% to 0.55% higher but skips the premium. Over five years, the math is close. Over ten, the premium often costs more than the rate discount saves.
The $1.5 million ceiling
Mortgage insurance is capped at homes priced up to $1.5 million. A buyer in Toronto with $140,000 down on a $1,499,000 home qualifies for the insured rate. A buyer with $305,000 down on a $1,525,000 home does not, even though they have more equity. The system creates a rate cliff at the insurance limit. The buyer just above the cap faces a higher rate despite putting more money in.
Why the system exists
The structure is not accidental. Canadian banking law prohibits federally regulated lenders from issuing a mortgage above 80% loan-to-value unless it is insured. The policy shifts housing market risk from the private sector to the government. During downturns, banks continue lending to first-time buyers because the loans are guaranteed. The tradeoff is that buyers with less equity get better pricing than buyers with more.
A 25% down payment signals stronger finances to most people. To a lender's balance sheet, it signals higher capital requirements and no external guarantee. The rate reflects what the loan costs the bank to carry, not what it says about you.
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