ARM vs. VRM: the two kinds of variable mortgage, explained.

No — both are priced off the lender's prime rate, which moves when the Bank of Canada changes its overnight rate, but they behave differently once prime actually moves. A fixed-payment variable mortgage keeps the regular payment constant; an adjustable-rate mortgage lets the payment itself move with prime.

In everyday Canadian usage, “variable mortgage” almost always refers to the fixed-payment structure — which is exactly why the distinction is worth spelling out explicitly rather than assuming a client already understands it. See our companion piece on fixed vs. variable mortgages for how this fits into the broader decision.

Bank of Canada research defines the trigger rate as the interest rate at which the interest portion of a fixed payment equals the full payment amount, leaving zero left over for principal. Below that rate, more of each payment goes to interest as prime rises, and less to principal — but the payment itself stays the same.

Once a mortgage reaches its trigger rate, the borrower is required to adjust their payment, make a prepayment, or otherwise address the balance, because the fixed payment amount can no longer even cover the interest owed. Each mortgage has its own individualized trigger rate specified in the contract.

An ARM sidesteps it structurally: the payment amount itself rises or falls directly with prime, so the principal portion stays comparatively stable and there's no fixed payment ceiling for rising interest to eventually overtake.

The trade-off is payment certainty — an ARM borrower sees their payment change with every prime-rate move, rather than the change being absorbed invisibly inside a constant payment until a trigger point is reached.

The fixed-payment structure is the dominant “variable” product sold by most Canadian lenders today. Adjustable-rate, payment-moving products exist and are offered by some lenders, but they represent a smaller share of the market.

That imbalance is exactly why a broker shouldn't assume from the word “variable” alone which mechanics apply — confirming which structure a specific lender's product actually uses takes one question and avoids a client being genuinely surprised later.

For a fixed-payment mortgage, confirm what happens operationally at that specific lender once the trigger rate is reached — some allow a limited amount of negative amortization before requiring action, others require an immediate payment increase. For an ARM, make sure the client is genuinely comfortable budgeting around a payment that can move without warning, not just the rate.

Running that comparison properly on every file is easier with support from Treadstone's fulfillment team for mortgage professionals, which keeps lender-specific trigger-rate policies on hand rather than re-researched on the fly.