Fixed and variable rental mortgages: what moves the rate and the payment?

A fixed mortgage rate offers interest-rate certainty for its term. A variable rate can move with the lender’s prime rate, but the payment response depends on the product. Some payments adjust; others initially stay the same while less of each payment reduces the debt.

For a rental, compare the cash required today, the debt likely to remain at renewal and the contractual response to rising rates. A stable withdrawal alone does not mean borrowing costs are stable.

What moves the rate

The Bank of Canada’s mortgage-pricing explanation identifies funding costs, risk, operating costs and competition as influences. Its policy rate affects short-term rates, including bank prime rates, but the Bank does not directly set your mortgage quote.

Fixed-rate offers respond to the cost of funding for the relevant period. Bond yields can be a useful market signal, but a particular bond yield is not a complete formula for a rental mortgage. A lender’s spread and your application still matter. An existing fixed rate generally stays fixed during its agreed term even when new offers change.

A variable quote is commonly expressed as lender prime plus or minus an agreed spread. Under a hypothetical prime-minus-0.50-percentage-point contract, 6% prime produces a 5.50% mortgage rate. If prime becomes 5.75% and the spread is unchanged, the mortgage rate becomes 5.25%. Those are invented rates, not current quotes or a forecast of a Bank of Canada decision.

Read when the change takes effect and whether the spread stays constant for the term. A rate hold for a variable offer also needs clarification: what is being held, the spread or an all-in rate?

Separate three payment structures

The Bank of Canada’s November 2022 trigger-rate note distinguishes variable mortgages with changing payments from those with fixed payments. Its historical estimates are not current prevalence figures.

Amortization is the repayment schedule, not the rate-guarantee period. If principal repayment slows, projected repayment can stretch. A projection on a statement does not give you a guaranteed extension at renewal.

Watch the interest portion, not just the payment

Consider a separate hypothetical daily-interest variable mortgage with CAD 400,000 outstanding, a CAD 2,200 payment and a 30-day period. Each row starts from the same balance with no intervening payment or deferred interest; these are alternative snapshots, not consecutive months. All values are CAD, before tax, excluding fees.

For example, interest at 6% is CAD 400,000 × 6% × 30 ÷ 365 = CAD 1,972.60. Subtracting it from CAD 2,200 leaves CAD 227.40 for principal.

At 7%, the payment is CAD 101.37 short of that period’s interest. What happens next depends on the contract; this table does not grant permission to add the shortfall to the loan.

The period-specific interest-only boundary can be estimated as:

$$r_t=A\times365/(P\times d)$$

Here, $r_t$ is the annual rate as a decimal at which the payment just covers this period’s interest, $A$ is the CAD payment, $P$ is the CAD balance and $d$ is days. CAD 2,200 × 365 ÷ (CAD 400,000 × 30) gives approximately 6.69%. Different period lengths and balances change this estimate. Obtain the lender’s disclosed trigger calculation for the actual mortgage.

Trigger rate and contractual action are different questions

A trigger rate is the point where the payment covers interest but no principal. The FCAC’s committee briefing distinguishes this from a trigger point tied to the balance exceeding a lender’s acceptable equity relationship. Contract terminology and responses vary.

For another product-specific limit, section 8 of CIBC’s Ontario standard charge terms, form 5453-2026/04 requires action when remaining amortization exceeds 40 years for the named variable products. This is a contractual action threshold in that form, not permission to assume 40-year financing everywhere.

Ask what notices, payment increases, lump sums or conversion requirements apply, and when. Request both the balance-based and amortization-based conditions, if present. If unpaid interest can be deferred, ask how interest on that amount is handled.

Choose around the property’s ability to absorb changes

At each rate change, compare the new required payment or allocation with actual rental cash and accessible reserves. Recheck the lender’s projected balance and renewal payment, especially if principal repayment has slowed. Investigate falling debt-service coverage alongside the full cash budget; a coverage ratio alone excludes some owner cash needs.

Before selecting a term, stress the property at higher payments and lower rental collections. If that exposes a funding gap, discuss payment structure, reserves and debt size before relying on an expected rate decline. Also compare break costs if a sale or refinance is plausible during the term.

For the calculation conventions behind the statement, read mortgage interest and first-payment timing.

Sources

• Bank of Canada — What's behind your mortgage rate. May 2020 explanatory article, not current rates. Accessed October 1, 2026.
• Bank of Canada — Variable-rate mortgages with fixed payments: Examining trigger rates. November 2022 analytical note; use definitions, not historical prevalence as current. Accessed October 1, 2026.
• FCAC — Variable rate mortgages with fixed payments; unregulated lending. February 13, 2024 committee briefing, descriptive not an individual contract. Accessed October 1, 2026.
• CIBC — Ontario Standard Charge Terms 5453-2026/04, Version A. Ontario named form 2026/04; signed product/charge terms govern. Accessed October 1, 2026.