Variable rate mortgage in Canada: VRM vs ARM and trigger rate risk
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By Editorial team
A $450,000 Canadian mortgage at prime minus 0.75% (contract rate 4.45%, with prime at 5.20%) carries a trigger rate near 6.61% (prime about 7.36%). That means prime needs to climb roughly 2.16 percentage points before the scheduled payment stops covering any principal at all. With a VRM, that moment has real consequences: your lender can require a payment increase immediately. With an ARM, there is no trigger rate - because the payment already moved every time prime did.
Most Canadian borrowers who chose variable in 2020 and 2021 did not know which structure they had. By 2023, many found out the hard way. This article explains the mechanical difference, shows what the trigger rate calculation looks like on a specific loan, and models the payment behavior of both structures under a rising-rate scenario.
The scenario modeled
We model two tabs: VRM - fixed payment and ARM - adjustable payment. Both start with the same loan amount and contract rate. Rate forecast steps apply at the start of contract year 2 (+1.25% prime) and year 3 (+0.75% prime). All calculations use Canadian semi-annual compounding.
| Input | Value |
|---|---|
| Purchase price | $560,000 |
| Down payment | $112,000 (20%) |
| Loan amount | $450,000 |
| Mortgage type | Variable (VRM - fixed payment) vs variable (ARM - adjustable payment) |
| Contract rate at origination | 4.45% (prime 5.20% minus 0.75%) |
| Amortization | 25 years |
| Payment frequency | Monthly |
| Country | Canada |
Modeled rate path (applied to both structures):
| Year | Prime rate | Contract rate |
|---|---|---|
| Origination | 5.20% | 4.45% |
| Year 1 renewal scenario | 6.45% | 5.70% |
| Year 2 renewal scenario | 7.20% | 6.45% |
The findings
At origination (prime 5.20%, contract rate 4.45%)
On a $450,000 loan at 4.45% over 25 years using Canadian semi-annual compounding, the scheduled monthly P&I payment is approximately $2,477.
| VRM - fixed payment | ARM - adjustable payment | |
|---|---|---|
| Monthly payment at origination | $2,477 | $2,477 |
| Interest in month 1 | $1,661 | $1,661 |
| Principal in month 1 | $816 | $816 |
| Payment changes when prime moves | No | Yes |
At origination they look identical. The difference only appears when prime moves.
After a 1.25% prime increase (prime 6.45%, contract rate 5.70%)
The rate step below reflects the first forecast row (month 13 in the schedule, entering contract year 2).
| VRM - fixed payment | ARM - adjustable payment | |
|---|---|---|
| Monthly payment | $2,477 (unchanged) | $2,794 |
| Monthly payment change | $0 | +$317/month |
| Interest portion | $2,081 | $2,081 |
| Principal portion | $397 | $714 |
| Months until paid off (remaining) | [PENDING: VRM amortization extension after rate step] | 288 months (unchanged from original 25-year path at this point) |
The ARM borrower absorbs a $317/month payment increase immediately. The VRM borrower keeps paying $2,477 - but most of what used to go to principal now goes to interest. The loan is amortizing slower than planned.
Trigger rate: when VRM payment covers interest only
The trigger rate is the contract rate at which the scheduled payment equals the interest-only amount on the current outstanding balance. For this scenario, with a $450,000 opening balance and a payment of $2,477/month:
| Metric | Value |
|---|---|
| Scheduled monthly payment | $2,477 |
| Contract rate that makes interest = $2,477/month | approximately 6.61% |
| Prime rate at trigger | approximately 7.36% (contract rate 6.61% = prime minus 0.75%) |
| Prime needs to rise from 5.20% | approximately 2.16 percentage points |
At the trigger point, every dollar of the $2,477 payment goes to interest. Principal does not decrease at all. After the trigger is crossed, each payment is insufficient to cover interest, and the outstanding balance actually grows (negative amortization).
What the trigger rate warning in the calculator shows
The calculator computes the trigger rate dynamically based on your current outstanding balance and scheduled payment. The color codes work as follows:
- Red: prime needs to rise 1% or less to hit trigger - high risk
- Orange: 1-2% rise required - moderate risk
- Amber: more than 2% rise required - lower risk
For this loan at origination, the trigger is about 2.16 percentage points away, which the calculator shows as amber.
Canadian context
The Bank of Canada raised the overnight rate 10 times between March 2022 and July 2023, moving from 0.25% to 5.00%. Prime rate followed, climbing from 2.70% to 7.20% over that period. For VRM holders who had locked in payments when prime was near historical lows, many crossed their trigger rates before mid-2023. In a November 2022 staff note, the Bank of Canada estimated that about 50% of variable-rate mortgages with fixed payments had already reached their trigger rate at typical variable rates near 5.1% - roughly 13% of all Canadian mortgages.
Source: Bank of Canada, "Variable-rate mortgages with fixed payments: Examining trigger rates," published November 2022, accessed April 2026. URL: https://www.bankofcanada.ca/2022/11/staff-analytical-notes-2022-19/
When this applies - and when it doesn't
This comparison applies when: You are considering a variable-rate mortgage in Canada and want to understand which structure you are signing. The VRM vs ARM distinction is not obvious from the rate alone - you need to read the contract or ask your lender directly. It applies especially if you are in a rising-rate environment or expect rates to move significantly during your term.
It doesn't apply when: You have a fixed-rate mortgage. Fixed-rate mortgages have no trigger rate, no payment variation mid-term, and no amortization extension risk. If you have already triggered on a VRM and are evaluating conversion to fixed, the relevant numbers are your current outstanding balance, remaining amortization, and the penalty to break or convert - see the renewal shock scenario for that path. For the broader fixed-vs-variable choice upstream, see fixed vs variable in Canada.
ARM borrowers: there is no trigger rate risk, but there is cash flow risk. When prime rises 0.25%, your payment rises the same day. On a $450,000 loan, each 0.25% prime increase adds roughly $64/month to the ARM payment at origination. After four consecutive 0.25% increases, that is about $256/month more than origination. You know about it immediately; you cannot defer it.
VRM borrowers after the trigger: once the trigger is crossed, most lenders require one of: (a) a one-time payment to reduce the balance, (b) a payment increase to restore principal reduction, or (c) conversion to a fixed rate. Conversion triggers a rate comparison and potentially a penalty. None of these options are optional at the lender's request.
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Frequently asked questions
- What is the difference between a VRM and an ARM in Canada?
- A VRM (Variable Rate Mortgage) keeps your payment constant when prime moves - only the principal and interest split changes. An ARM (Adjustable Rate Mortgage) adjusts your actual payment immediately when prime changes. Both carry a variable contract rate tied to prime; the distinction is whether the payment absorbs the movement or whether the amortization does.
- How is the trigger rate calculated?
- The trigger rate is the contract rate at which your scheduled payment exactly equals the monthly interest charge on your current outstanding balance. Below the trigger, some portion of each payment reduces principal. At or above it, the payment covers interest only, or less. The formula depends on your outstanding balance and original payment amount, so the trigger rate shifts slightly as you pay down the loan.
- If prime rises 1%, how much does an ARM payment increase on a $450,000 mortgage?
- On a $450,000 loan at 4.45% over 25 years with Canadian semi-annual compounding, a 1% prime increase (raising the contract rate to 5.45%) brings the monthly ARM payment from approximately $2,477 to roughly $2,738 - an increase of about $260/month. The exact amount depends on the remaining balance at the time of adjustment.
- Can I switch from a VRM to a fixed rate before the trigger is hit?
- Yes. Most lenders allow conversion to a fixed rate at any time during the term, though you give up the variable rate and must accept whatever fixed rate the lender offers at conversion. Breaking a VRM before term end may incur a penalty, typically three months' interest rather than the interest rate differential used for fixed-rate mortgages - confirm with your lender.
- Does the trigger rate change as I pay down the loan?
- Yes. As your outstanding balance decreases, the interest portion of each payment also decreases, so your original fixed payment covers a larger share of interest at lower rates. The trigger rate effectively rises slightly over time as the loan amortizes normally - meaning it becomes less likely to be hit in later years than in the first few years of the term.