Canadian Mortgage Amortization Guide: 25 vs 30 Years (2026)

What Is Amortization and How Does It Work?

Amortization is the length of time required to pay off a mortgage completely if all payments are made as scheduled. It is different from the mortgage term.

Mortgage term: The length of the current loan agreement (typically 1-5 years in Canada). At the end of the term, the mortgage renews at current rates.

Amortization period: The total repayment schedule (25 or 30 years). Each term is a portion of the amortization period.

Example: A 25-year amortization mortgage with a 5-year term. After the 5-year term, the remaining balance is renewed — but the borrower has only 20 years of amortization remaining, not 25.

The amortization period determines your monthly payment. Longer amortization = lower monthly payment but more total interest paid.

Canadian Mortgage Math: Semi-Annual Compounding

Canadian mortgages use semi-annual compounding under the Interest Act — a legally required calculation different from most countries.

US mortgages use monthly compounding. Canadian mortgages use semi-annual (twice-yearly) compounding. This means lenders compound interest twice per year, not monthly. Using monthly compounding for Canadian mortgages gives incorrect results.

The effective monthly rate formula for Canadian mortgages:

// Canadian semi-annual compounding:
Effective Annual Rate = (1 + annual_rate/2)^2 - 1
Monthly Rate = (1 + EAR)^(1/12) - 1

// Example at 5.0% nominal rate:
EAR = (1 + 0.05/2)^2 - 1 = 5.0625%
Monthly Rate = (1 + 0.050625)^(1/12) - 1 = 0.41246%

// Compare to US monthly compounding:
US Monthly Rate = 5.0% / 12 = 0.41667% (slightly higher)
// Canadian rate is LOWER than US rate at same nominal rate

Monthly Payment Comparison: 25 vs 30 Years

Monthly payment comparison at 5.0% nominal rate (semi-annual compounding):

Total Interest Cost: 25 vs 30 Years

The monthly savings of a 30-year amortization come at a significant long-term cost:

Example: $600,000 mortgage at 5.0% (assuming rate stays constant for illustration — actual rate changes at each renewal):

25-year amortization: • Monthly payment: $3,488 • Total payments: $3,488 × 300 = $1,046,400 • Total interest: $1,046,400 - $600,000 = $446,400

30-year amortization: • Monthly payment: $3,183 • Total payments: $3,183 × 360 = $1,145,880 • Total interest: $1,145,880 - $600,000 = $545,880

Cost of 30-year vs 25-year: $99,480 more in total interest.

However, this assumes rates stay constant. In practice, both borrowers renew every 5 years at market rates. The real difference is the extra 5 years of payments × remaining balance at year 25.

Who Can Get 30-Year Amortization in Canada?

Since 2024, 30-year amortization is available in two scenarios:

Conventional (20%+ down) — 30-year always available: • Any borrower with 20%+ down payment • Any property type (owner-occupied, investment, rental) • Any purchase price • No first-time buyer requirement

Insured/High-ratio — 30-year requires all of: • Must be a first-time home buyer (or haven't owned a home in the last 4 years) • Must be purchasing new construction (newly built property) • Purchase price must be under $1,000,000 • Down payment 5-19.99% (insured mortgage) • CMHC amortization surcharge: +0.20% premium

When Does a 30-Year Amortization Make Sense?

Arguments for 30-year amortization:

1. Qualification: Lower monthly payment can mean qualifying for a larger mortgage or qualifying at all when TDS is borderline. On a $700,000 mortgage, 30-year vs 25-year saves $350/month — potentially the difference between 44% TDS and 47% TDS.

2. Cash flow: Clients in higher-cost cities (Toronto, Vancouver) are often income-qualified but cash-flow-constrained. $300-500/month lower payment is meaningful.

3. Investment: If client invests the monthly savings at a return higher than their mortgage rate, 30-year can mathematically win. At 5% mortgage rate and 7%+ investment return, investing the $300-500/month monthly savings theoretically outperforms accelerated repayment.

Arguments against 30-year amortization:

1. Interest cost: $90,000-100,000+ more interest over the life of the mortgage 2. Slower equity buildup: After 5 years, the 30-year borrower has paid $20,000-30,000 less principal than the 25-year borrower 3. Availability: Not available for insured mortgages except for first-time buyers purchasing new construction under $1M

Amortization and the Stress Test

A longer amortization reduces monthly payments, which directly improves GDS/TDS qualification ratios.

Practical implication: Borderline deals that fail at 25-year amortization often pass at 30-year.

Example: $750,000 mortgage, $130,000 income, $500/month car payment • At 25yr, 7.5% qualifying rate: Payment $5,436 → TDS = ($5,436 + $500 + tax/heat) ÷ $10,833 = 58% — FAILS • At 30yr, 7.5% qualifying rate: Payment $4,961 → TDS = ($4,961 + $500 + tax/heat) ÷ $10,833 = 54% — still fails • Key lesson: Amortization helps TDS but may not be enough alone for high-value deals

BIPS calculates GDS/TDS at both 25 and 30-year amortization automatically, showing whether the longer amortization changes which lenders qualify the deal.