The 15% Down Payment Gets a Better Rate Than 25% Because the Bank Isn't Taking Your Risk

A buyer in Kelowna put down 15% on a $640,000 townhouse in November and locked in at 4.74%. Her sister, who saved longer and put down 30% on a similar property across town, got 5.09%. Same credit score. Same lender. The difference was insurance.

When you put less than 20% down on a property in Canada, the mortgage becomes high-ratio. That triggers a legal requirement: default insurance from one of three approved providers, CMHC, Sagen, or Canada Guaranty. The premium runs between 2.8% and 4% of the mortgage amount, usually rolled into the loan. Most buyers see that cost and assume they're paying more overall for the privilege of borrowing with less equity. They're half right.

What the premium buys is not protection for you. It's protection for the bank.

The lender isn't carrying your default risk anymore

Default insurance works like this. You buy a house for $500,000 with $75,000 down. Your mortgage is $425,000. Because your down payment is 15%, the loan requires insurance. If you default, job loss, illness, divorce, whatever, the insurer pays the lender. Not you. The bank gets made whole. You still lose the house, you still take the credit hit, but the lender's loss is capped at whatever the insurer doesn't cover, which in most scenarios is close to zero.

From the lender's perspective, that insured mortgage is now a fundamentally different asset. It's government-backed risk, packaged and sold off their balance sheet or held at a capital weighting so light it barely moves their liquidity requirements. A conventional mortgage, 20% or more down, no insurance, sits on their books as full-exposure lending. If that borrower defaults and the property sells for less than the outstanding balance, the lender eats the shortfall.

So they price accordingly. The high-ratio mortgage with insurance behind it gets the sharp rate. The conventional mortgage without it gets 25 to 50 basis points worse, sometimes more, because the bank is actually taking a risk.

The premium still costs you, just not where you think

A 15% down payment on a $600,000 home means a $510,000 mortgage. The insurance premium at that loan-to-value ratio is roughly 3.1%, or about $15,800. That gets added to the principal, so you're now carrying $525,800 in debt. You pay interest on that extra $15,800 for the life of the mortgage.

But the rate you get on that $525,800 is often a quarter point better than what the 25% down buyer gets on their smaller, uninsured loan. Over five years, depending on the rate environment and the exact spread, that difference can offset a meaningful chunk of the premium. It doesn't always break even, sometimes the conventional buyer still pays less in total interest, but the gap is far narrower than the sticker price of the insurance premium suggests.

The real cost is liquidity. You paid $15,800 up front (even if financed) for access to capital you didn't have. The uninsured borrower paid nothing but held more cash at close. Which of those is better depends entirely on what you'd have done with the extra savings if you'd waited.

First-time buyers consistently get this backward

The standard advice is to save for 20% to "avoid paying for mortgage insurance." It sounds disciplined. In a market where prices are rising 6% a year, waiting two more years to save an extra $40,000 means the house you were targeting is now $75,000 more expensive. You saved the premium. You lost the house, or you stretched into a worse one.

The rate advantage on insured mortgages has been consistent since CMHC-backed lending became the standard structure in the early 2000s. It shows up in rate sheets. It shows up in broker commission structures, where insured deals often pay better because they're easier to place. Lenders like them because the capital treatment is favorable and the default risk is externalized.

None of that helps the borrower who defaults. The insurance protects the institution, not the household. But in the narrow frame of rate competition, the 15% down buyer is walking into the room with a balance sheet the bank likes better than the 25% down buyer's. That's the trade.