I Bet You Didn’t Know This About Variable Rate Mortgages

Most people talk about “the variable rate mortgage” like it’s one single product. It isn’t. There are actually two structurally different versions of it, a hidden threshold that can quietly work against you, a rate hold trick almost nobody uses, and a conversion privilege that doesn’t work the way most homeowners assume. Here’s what usually only gets explained after something’s already gone sideways.

There are actually two kinds of variable rate mortgages

The first is an Adjustable-Payment variable rate mortgage. When prime rate moves, your monthly payment moves with it — up when prime rises, down when prime falls. What stays fixed is your amortization; the number of years it takes to pay off the loan never changes. 

The second is a Static-Payment variable rate mortgage. Here, your payment stays exactly the same no matter what prime does. Behind the scenes, every prime rate move recalculates the split between interest and principal within that unchanged payment. When rates rise, more of your payment goes to interest and less to principal — which quietly stretches your real amortization, even though the payment amount on paper never moves. Conversely, when prime drops, more goes to principal, and your amortization shortens accordingly.

Both types track prime identically — the rate itself is the same. The difference is simply which variable the lender chose to hold constant: your payment, or your amortization.

The trigger rate: the part almost nobody explains up front

With a static payment variable rate mortgage, there’s a specific threshold called the trigger rate. Once prime climbs high enough that your fixed payment no longer covers the interest owed that month, the shortfall gets added back onto your mortgage balance instead — a process known as negative amortization. Your real payoff timeline starts silently extending, and eventually the lender will require a change: a lump-sum payment, an increased payment, or a switch in structure.

This is exactly what a large number of Canadian variable rate holders experienced during the aggressive rate-hiking period of recent years, and many had never heard the term “trigger rate” until it applied to them directly.

Yes, you can actually get a rate hold on a variable rate mortgage

A common misconception is that a variable rate mortgage can’t be rate-held, since the rate itself moves with prime. That’s not quite right. What gets held isn’t a fixed number — it’s the discount.

A variable rate mortgage is priced as prime, minus a discount (for example, prime minus 0.75%). Prime is free to move with the Bank of Canada, but that discount — the spread off prime — is exactly what gets locked in during a rate hold window.

Here’s the part that surprises people further: those discounts change. Lenders adjust them based on funding costs and competitive pressure, and unlike a Bank of Canada announcement, these adjustments happen quietly and more frequently than most borrowers assume. Locking the discount during a hold can be the difference between a strong variable rate and a mediocre one by the time you close. Click Here for more information on how rate holds work from a recent blog.

Your one-time conversion privilege isn’t what most people think

Nearly every variable rate mortgage includes a one-time conversion privilege — the ability to lock into a fixed rate mid-term without breaking the mortgage or paying a penalty. The catch: you don’t get to lock in your original variable contract rate. You get the lender’s prevailing fixed rate, for a term matching however many years remain in your variable term (or shorter, if preferred).

So if you’re two years into a five-year variable term and decide to convert, you’d be offered the current fixed rate for a three-year term — matching your three years remaining — not a preview of rates from when you first signed. It’s also worth knowing that the prevailing rate offered on conversion isn’t always the lender’s best, most heavily discounted promotional pricing. It’s worth asking directly and comparing rather than assuming.

The break penalty difference — and why it’s not quite as simple as people think

Breaking a variable rate mortgage early triggers a penalty of just three months’ interest — a straightforward calculation based on your balance and current rate. Breaking a fixed rate mortgage triggers the greater of three months’ interest or the interest rate differential (IRD), which can be substantially more expensive, especially if rates have dropped since the original fixed rate was signed.

Many people conclude from this that variable penalties are simply cheaper than fixed penalties. That’s not entirely accurate — it’s more that variable eliminates the possibility of an exorbitant IRD outcome. With variable, the penalty is always predictable: three months’ interest, no surprises. With fixed, the number isn’t known until the math runs, and sometimes that math is ugly.

A few more things worth knowing

• The stress test applies the same way: Variable rate mortgages must still qualify at the higher of the contract rate plus 2%, or the government’s minimum qualifying rate — going variable doesn’t create an easier qualification path.
• Prime rate is technically bank-specific: Each lender sets its own prime rate, but almost all maintain the same one. In practice nearly all Canadian lenders move prime in lockstep with the Bank of Canada’s overnight rate, so divergence is rare, but structurally it’s each lender’s own posted number.

Adjustable vs. static payment variable rate mortgages, side by side