Two people can sign a variable-rate mortgage on the exact same day, at the exact same rate, from the exact same bank, and walk away with mortgages that behave in completely different ways the moment interest rates move. One of them watches their monthly payment climb or drop automatically. The other keeps paying the same amount every month no matter what happens to rates, while something invisible shifts underneath that payment instead. Most homeowners never learn which version they actually signed up for until a rate change forces the question, and by then the answer matters a lot more.
A variable-rate mortgage ties your interest rate to your lender’s prime rate rather than locking it in for the term. Your rate is quoted as prime plus or minus a set discount, and it moves automatically whenever your lender’s prime rate changes, usually within a day or two of a Bank of Canada rate decision. What happens to your actual monthly payment when that shift occurs, though, depends entirely on which of the two variable structures your mortgage uses.
How the rate itself gets built
Your lender doesn’t invent your variable rate out of nowhere. It starts with prime rate, which currently sits at 4.45 percent across all six major Canadian banks, according to Ratehub’s live rate tracking, and then subtracts (or occasionally adds) a discount negotiated when you signed. A mortgage quoted as prime minus 0.80 percent, for example, currently carries an effective rate of 3.65 percent. That discount is the one part of a variable rate that stays fixed for your entire term. Prime itself will keep moving with the Bank of Canada’s decisions, but the size of your discount off prime doesn’t change unless you renegotiate or renew, which is exactly why shopping around for the best mortgage rates on offer at signing matters more than most people realize.
Take a $450,000 mortgage on a 25-year amortization at that 3.65 percent effective rate. The monthly payment works out to roughly $2,290. If prime rose by half a percentage point tomorrow, that same mortgage at 4.15 percent would jump to somewhere around $2,410 a month, an extra $120 that shows up the next billing cycle with no warning letter required. That’s the part people underestimate about variable mortgages. Rate changes aren’t gradual or negotiated. They land automatically, on schedule, whether your budget is ready for them or not.
The two structures hiding under one label
Here’s where “variable rate” stops meaning one single thing. Most of Canada’s big banks sell variable mortgages with a fixed payment structure, while monoline and mortgage-only lenders more often sell the adjustable-payment version, and the two behave completely differently once rates start moving.
With an adjustable-rate mortgage, your monthly payment itself moves with prime. Rates go up, your payment goes up immediately. Rates come down, your payment drops immediately. The split between principal and interest inside that payment doesn’t change much, so your amortization schedule stays roughly on track no matter which direction rates move.
With a fixed-payment variable mortgage, the monthly amount you’re billed stays exactly the same even as your rate moves. What changes instead is the split inside that payment. When prime rises, a bigger slice of your fixed payment goes toward interest and a smaller slice chips away at principal. Your bill looks stable from the outside while your amortization is quietly stretching out behind the scenes.
The trigger rate, and why it matters more than most fixed-payment borrowers realize
If your mortgage uses the fixed-payment structure, there’s a specific point worth knowing about called the trigger rate. It’s the interest rate at which your fixed monthly payment stops covering any principal at all and goes entirely toward interest. Push past that point, and the interest owed can actually exceed what you’re paying each month, meaning your outstanding balance starts growing instead of shrinking even though every payment is being made on time.
This isn’t a theoretical risk. Bank of Canada research found that close to half of all fixed-payment variable mortgages had reached their trigger rate by late 2022, during the fastest run of rate hikes the country had seen in decades. Most lenders will reach out before a borrower gets there, offering to raise the payment, accept a lump-sum paydown, or extend the amortization to bring things back in line, but you’re not contractually forced to act until you hit what’s called the trigger point, where the balance owed actually exceeds the original loan amount. Prime has held steady at 4.45 percent since late October 2025, most recently confirmed by the Bank of Canada’s July 2026 hold, so this isn’t the live concern it was during the 2022 hiking cycle, but it’s still worth knowing your own trigger rate if you hold this structure, since the next rate cycle won’t announce itself in advance.
What it actually costs to get out early
Life changes mid-mortgage more often than people plan for, and variable mortgages have a real advantage here worth knowing about before you need it. Breaking a closed variable-rate mortgage before your term ends typically costs three months’ interest, full stop. Fixed-rate mortgages, by comparison, usually carry the greater of three months’ interest or an interest rate differential calculation that can run into the thousands of extra dollars depending on how far rates have moved since you signed.
That three-month penalty is one of the clearest practical reasons some borrowers choose variable even when the headline rate isn’t the cheapest option on the table. If there’s a real chance you’ll sell, refinance, or need to break the mortgage before the term is up, whether that’s a job relocation, a growing family needing more space, or just general uncertainty about the next five years, that lower, more predictable exit cost is worth factoring into the decision alongside the rate itself.
What the numbers say over the long run
The most-cited research on this question comes from a 2001 study by York University finance professor Moshe Milevsky, who tracked Canadian fixed and variable mortgage rates from 1950 through 2000 and found that variable-rate borrowers came out ahead roughly 88 to 90 percent of the time. The logic behind that result is straightforward. Lenders charge a premium for the certainty a fixed rate provides, and over long stretches of mortgage history, that premium has usually cost more than the actual rate volatility it was meant to protect against.
That track record comes with a real asterisk, though. The exceptions cluster around periods of aggressive, fast-moving rate hikes, exactly like the stretch between March 2022 and January 2023, when the Bank of Canada delivered eight consecutive increases and pushed variable rates above comparable fixed rates for most of that window. History leaning toward variable over a fifty-year average doesn’t tell you anything about which five-year term you happen to be signing into, and a borrower locking in during a sharp hiking cycle can absolutely end up on the losing side of that long-run average.
Who this actually fits
Variable rates suit a specific kind of borrower more than others. If your budget has real room to absorb a payment increase without scrambling, if you value the lower breakage penalty because your five-year plans genuinely aren’t settled, or if you’re comfortable converting to a fixed rate mid-term if the outlook shifts, a variable mortgage can be a reasonable and often cheaper choice. If a payment jump of a few hundred dollars would seriously strain your monthly budget, or the idea of an unpredictable bill keeps you up at night regardless of the long-run odds, that stress is a real cost too, even if the math technically favours variable.
If you’re weighing this decision for a Manitoba purchase or renewal specifically, our side-by-side look at fixed and variable rates in Winnipeg walks through how the two options compare using current local numbers. And if a payment increase would genuinely put your mortgage at risk rather than just squeeze the budget, it’s worth reading through what actually happens once a missed payment turns into something more serious before you’re in that position, not after.
Deciding whether variable fits your situation
Start by finding out, in plain terms from your own lender, whether your existing or prospective mortgage uses the adjustable-payment or fixed-payment structure, since that single detail changes how a rate move actually reaches your budget. Run your own numbers through a mortgage calculator using a rate a full percentage point higher than today’s, not to predict the future but to see honestly whether your budget could absorb that shift without real strain, and double-check what a longer amortization would do to that same payment using our amortization calculator while you’re at it. Compare what you’d find against current mortgage rates across Canada and the fixed-rate side of the market before committing either way, and if you want a second set of eyes on the tradeoff, a mortgage broker who can run the comparison with your actual numbers is worth the conversation before you sign anything.
