The Math: Mortgage Payoff vs Investing
Assumptions: $300,000 Remaining Mortgage, 20 Years Left, $500/Month Extra
| Strategy | Mortgage Rate | Investment Return | Net Result After 20 Years |
|---|---|---|---|
| Pay off mortgage early | 5.00% | — | Mortgage-free in ~13 years, save ~$84,000 in interest |
| Invest (non-registered) | 5.00% | 7% gross (5.5% after tax) | ~$220,000 portfolio, still owe mortgage until year 20 |
| Invest (TFSA) | 5.00% | 7% (tax-free) | ~$260,000 portfolio, still owe mortgage until year 20 |
Breakeven: When Does Investing Win?
| Mortgage Rate | Minimum Investment Return Needed (Non-Reg, 30% Tax) | Minimum Return in TFSA |
|---|---|---|
| 3.00% | 4.3% | 3.0% |
| 4.00% | 5.7% | 4.0% |
| 5.00% | 7.1% | 5.0% |
| 6.00% | 8.6% | 6.0% |
| 7.00% | 10.0% | 7.0% |
In a TFSA, you only need to match the mortgage rate to break even. In a non-registered account, you need a higher return due to taxes on gains.
20-Year Comparison: $500/Month Extra
Scenario: 5% Mortgage Rate, 7% Investment Return
| Option | Year 5 | Year 10 | Year 15 | Year 20 |
|---|---|---|---|---|
| Mortgage payoff | ||||
| Mortgage balance | $218,000 | $118,000 | $0 (paid off ~year 13) | $0 |
| Money saved (interest) | $18,000 | $52,000 | $84,000 | $84,000 + 7 years of free cash |
| Invest in TFSA | ||||
| Portfolio value | $35,000 | $86,000 | $158,000 | $260,000 |
| Mortgage balance | $247,000 | $183,000 | $105,000 | $0 |
| Net worth advantage | Investing | Investing | Investing | Investing by ~$176,000 |
When to Pay Off the Mortgage
| Situation | Why Pay Mortgage |
|---|---|
| Risk-averse personality | Guaranteed return; sleep better at night |
| Mortgage rate > 6% | Harder for investments to beat consistently |
| Near retirement | Want to eliminate fixed costs before retirement income drops |
| Variable rate mortgage | Rate could spike; paying down reduces exposure |
| No TFSA/RRSP room | Without tax shelter, investment advantage shrinks |
| Already have substantial investments | Diversify by eliminating debt |
| Short time horizon (< 5 years) | Market risk too high short-term |
| Unstable income | Reducing fixed obligations provides safety |
When to Invest Instead
| Situation | Why Invest |
|---|---|
| Have TFSA room | Tax-free gains easily beat mortgage rate |
| Mortgage rate is low (under 4-5%) | Historically, equities return 7-10% long-term |
| Long time horizon (10+ years) | More time for compounding and recovery from dips |
| Employer RRSP match | Free money — always take the match first |
| Young (under 45) | Decades of growth ahead |
| Comfortable with volatility | Can handle 30%+ drops without panic selling |
| Building RRSP for tax deduction | Tax refund can be reinvested |
| Want liquidity | Investments are accessible; mortgage equity is not |
The Best Strategy: Do Both
Priority Order for Extra Cash
| Priority | Action | Why |
|---|---|---|
| 1 | Employer RRSP match | 50-100% instant return (free money) |
| 2 | High-interest debt (credit cards) | 20%+ interest — always pay first |
| 3 | Max TFSA | Tax-free growth beats most mortgage rates |
| 4 | Max RRSP (if higher tax bracket) | Tax deduction + tax-deferred growth |
| 5 | Split remaining 50/50 | Half to mortgage lump sum, half to non-reg investment |
Example: $1,000/Month Available
| Allocation | Amount | Return/Savings |
|---|---|---|
| TFSA (index ETFs) | $583 ($7,000/yr) | 7% tax-free growth |
| Mortgage lump sum | $417/month extra | 5% guaranteed return |
| Combined 20-year result | Mortgage paid off ~5 years early + $180,000 TFSA |
Tax Considerations
| Strategy | Tax Impact |
|---|---|
| Mortgage payoff | No tax benefit (mortgage interest is not deductible on primary residence in Canada) |
| TFSA investing | Zero tax on all gains |
| RRSP investing | Tax deduction now; taxed on withdrawal (ideally at lower retirement rate) |
| Non-registered investing | Capital gains at 50% inclusion; dividends get dividend tax credit |
| Smith Manoeuvre | Convert mortgage interest to tax-deductible by borrowing to invest |
The Smith Manoeuvre (Advanced)
| Step | Details |
|---|---|
| 1 | Get a re-advanceable mortgage (HELOC + mortgage combo) |
| 2 | As you pay down mortgage principal, HELOC available increases |
| 3 | Borrow from HELOC to invest in income-producing assets |
| 4 | HELOC interest becomes tax-deductible (since borrowed to invest) |
| 5 | Investment income helps pay mortgage faster |
| Risk | If investments decline, you still owe the HELOC |
| Best for | Financially sophisticated, long time horizon, comfortable with leverage |
Emotional vs Mathematical Decision
| Factor | Pay Off Mortgage | Invest |
|---|---|---|
| Certainty | 100% guaranteed return | Variable/uncertain |
| Sleep-at-night factor | Very high | Depends on personality |
| Flexibility | None (equity locked in house) | High (liquid) |
| Regret potential | Low | Moderate (if market drops) |
| Excitement | Low | Higher (watching portfolio grow) |
| Behavioural risk | Low (set it and forget it) | Higher (temptation to time market) |
Scenario Calculator
$200,000 Mortgage, 5% Rate, 20-Year Amortization
| Extra Payment/Month | Years Saved | Interest Saved | Alternative: Invest in TFSA at 7% |
|---|---|---|---|
| $200 | 4.5 years | $38,000 | $123,000 (20 years) |
| $400 | 7 years | $59,000 | $207,000 (20 years) |
| $600 | 9 years | $72,000 | $299,000 (20 years) |
| $1,000 | 11 years | $82,000 | $520,000 (20 years) |
Investing in TFSA at 7% generates significantly more wealth than mortgage payoff at 5%, but it is not guaranteed.
Bottom Line
| Your Situation | Recommendation |
|---|---|
| Mortgage rate under 4%, have TFSA room | Invest (TFSA) |
| Mortgage rate 4-6%, have TFSA room | Split: max TFSA first, then mortgage extra |
| Mortgage rate over 6% | Pay down mortgage aggressively |
| No TFSA/RRSP room | Pay down mortgage (guaranteed return) |
| Near retirement (5-10 years) | Pay down mortgage (reduce fixed costs) |
| Young, aggressive saver | Max TFSA → RRSP → then consider mortgage |
| Employer RRSP match available | Always take the match first, then decide |