The 0.20% surcharge for a 30-year amortization is not one flat rule: CMHC's own premium page applies it to any insured mortgage that takes 26-30 years to pay off, while CMHC's August 2024 notice frames the same 0.20% specifically for qualified first-time buyers of newly built homes. A blended amortization (part of the loan re-amortized on renewal) carries a separate, larger 0.60% surcharge — a different rule this calculator does not model. CMHC's own price ceiling is a home valued strictly "below C$1,500,000", and insurance is only mandatory in the first place because OSFI's Guideline B-20 requires any mortgage above 80% loan-to-value to carry it.
Two sources describe the same 0.20% surcharge differently
The calculator above adds a flat 0.20 percentage points to your premium rate whenever you select a 30-year amortization. That number comes from two CMHC documents that frame its scope differently, and the difference matters for who can actually use it. CMHC's professional-facing premium page states the surcharge in general terms: "An amortization period beyond 25 years is subject to a 0.20% surcharge," with no buyer-type restriction stated on that page.
CMHC's August 2024 revision notice describes the same 20-basis-point figure as being applied specifically "to qualified first-time homebuyers opting for the increased amortization of 30 years," and ties it to the program that extended insured amortization to 30 years for first-time buyers and buyers of new construction, effective August 1, 2024. Read together, both pages agree on the 0.20% number; the notice is the narrower, buyer-eligibility-specific statement, while the professional premium page is the general premium-schedule statement. If you don't fit the first-time-buyer/new-construction eligibility, confirm with your lender that 30-year insured amortization is actually available to you before assuming the 0.20% surcharge applies.
| Scenario | Surcharge on premium rate | Source |
|---|---|---|
| Any insured mortgage, 26-30yr amortization | +0.20 points | CMHC premium information page |
| First-time buyer, new-construction home, 30yr | +0.20 points (same rate, narrower eligibility) | CMHC Aug. 2024 notice |
| Blended amortization on renewal | +0.60 points (separate rule) | CMHC premium information page |
Figures per CMHC, retrieved 2026-09-21. This calculator models the 26-30yr surcharge only; it does not model the blended-amortization surcharge.
Blended amortization is a separate, three-times-larger surcharge
A blended amortization happens when part of your mortgage is re-amortized to a longer schedule at renewal — for example, a lender extending part of the balance to help a borrower manage a payment shock. CMHC's premium information page states this triggers its own surcharge: "A blended amortization period is subject to a 0.60% surcharge" — three times the 0.20% charged for a straightforward 26-30 year amortization. The two surcharges are not interchangeable and should not be added together or confused; this calculator's 30-year toggle applies the 0.20% figure only. If your lender is proposing a blended amortization at renewal, ask them directly whether the 0.60% surcharge applies to your specific structure, and see the mortgage renewal calculator for how a renewal changes your payment.
The C$1.5M price cap is a strict ceiling, not a round number
CMHC's own eligibility page states the purchase price for an insured homeowner loan "must be below C$1,500,000" — worded as strictly less than the cap, not "up to and including" it. A home listed at exactly C$1,500,000 is the kind of edge case worth confirming directly with your lender or a CMHC-approved insurer before assuming insurability, rather than treating the number as a soft round figure.
Why default insurance exists: OSFI's high-ratio rule
CMHC insurance is not just a lender preference — it is a regulatory requirement. OSFI's Guideline B-20 sets the underlying rule for federally regulated lenders: any mortgage with a loan-to-value ratio above 80% (a "high-ratio" mortgage, meaning a down payment under 20%) must be insured. That is the regulatory floor this calculator's premium tiers sit under — once your down payment clears 20% of the purchase price, you move to an uninsured ("conventional") mortgage and this calculator's premium does not apply. For the qualifying-rate math a lender runs alongside insurance on any mortgage, see the mortgage calculator.
Methodology
Premium-tier and PST figures are read directly from this calculator's own logic (src/lib/calculators/ca) and cross-checked against CMHC's mortgage loan insurance cost page and CMHC's premium information page. The worked down-payment example is arithmetic shown step by step from the tiered rule on CMHC's general requirements page. No figure in this article is estimated or drawn from a non-government source.
Sources
- CMHC — CMHC mortgage loan insurance cost — accessed 2026-09-21
- CMHC — Premium information for homeowner and small rental loans — accessed 2026-09-21
- CMHC — CMHC revises homeowner mortgage loan insurance premiums — accessed 2026-09-21
- CMHC — What are the general requirements to qualify for homeowner mortgage loan insurance — accessed 2026-09-21
- OSFI — Guideline B-20: Residential Mortgage Underwriting Practices and Procedures — accessed 2026-09-21