Paying Down the Mortgage vs Investing

When you have extra cash, the question of whether to pay down mortgage or invest comes down to comparing a guaranteed return with an uncertain one. A mortgage prepayment delivers a return equal to your mortgage rate, because every dollar you pay down stops accruing interest at that rate, and that saving is effectively tax-free. Investing offers the possibility of a higher return, but with no guarantee, and outside a registered account the gains may be taxable. There is no universal answer, only a framework you can apply to your own situation.

This guide sets out that framework. It is general information, not investment advice, and it deliberately avoids recommending one path over the other.

The two options in plain terms

Paying down the mortgage is a form of saving. You reduce a debt that charges interest, so the benefit is measured in interest you no longer pay. The return is fixed at your mortgage rate and known in advance, assuming a fixed rate for the relevant period.

Investing means putting the same cash into assets that may grow in value or produce income. The return is unknown and can be negative in any given period. In exchange for that uncertainty, the expected return over the long run may exceed your mortgage rate, though nothing guarantees it.

Comparing returns: guaranteed versus uncertain

The comparison is not simply mortgage rate versus investment return. Because the interest saved on a mortgage is not taxed, the investment must earn more than the mortgage rate, after tax, to come out ahead in a taxable account. Inside a registered account such as a TFSA or RRSP, the tax comparison changes.

The tax angle

Interest saved by prepaying a non-deductible mortgage is a tax-free benefit, so its after-tax value equals its headline value. An investment return, by contrast, may be reduced by tax on interest, dividends, or capital gains, depending on the account and the type of income.

That is why the relevant question is not "which return is higher" but "which after-tax return is higher." A mortgage at a given rate may be more attractive than a taxable investment with a similar expected return, because the mortgage return is untaxed. Within a TFSA, the investment return is also untaxed, which narrows the gap.

Registered accounts and first-home goals

If your goal is a first home, some registered accounts are designed for it. The First Home Savings Account (FHSA) allows contributions that may be deductible and withdrawals for a qualifying home purchase that may be tax-free, and the RRSP Home Buyers' Plan allows a temporary withdrawal from an RRSP to buy or build a qualifying home, subject to conditions and repayment rules.

Those programs can change the trade-off, because money directed there may receive a tax benefit that a mortgage prepayment does not. The rules are detailed, so confirm the current conditions with the Canada Revenue Agency and see the First Home Savings Account guide before relying on them.

Liquidity and risk

Money paid into a mortgage is difficult to access. Getting it back generally means borrowing against the home or selling, both of which carry cost and risk. Investments are usually more liquid, which matters if you might need the money for an emergency, a career change, or an opportunity.

Risk tolerance is the other half. A guaranteed return equal to your mortgage rate may be attractive to someone who values certainty, while an investor with a long horizon and the capacity to ride out volatility may accept a wider range of outcomes. Neither preference is wrong; they are simply different positions, and the right one for you depends on your temperament and your capacity to absorb a loss.

Who might lean each way

• Lean toward prepayment if you value certainty, dislike debt, hold a high mortgage rate, or have limited room in registered accounts.
• Lean toward investing if you have a long horizon, an emergency fund already in place, and room in tax-sheltered accounts.
• Consider a split if you want both the guaranteed saving and some liquidity, provided your prepayment privileges allow it.
• Prioritise high-interest debt first in most cases, because its cost usually exceeds both alternatives.

Whichever direction you lean, use the right tool for the mortgage side. The prepayment privileges guide explains how much you can pay without a penalty, and how to pay off your mortgage faster covers the full set of options.

A framework, not a recommendation

Work through four questions: What is my mortgage rate, and is it fixed or variable? What after-tax return would an investment need to beat it? How likely am I to need this cash before the mortgage is paid off? And how would I feel if the investment fell while the mortgage balance stayed the same? Your answers point to a direction, but the decision is yours, and a qualified financial professional can help you apply it to your full picture.

If retirement is part of your horizon, the same trade-off appears in planning to be mortgage-free in retirement. Estimate the prepayment side with the mortgage prepayment calculator, and confirm your annual prepayment allowance before committing to any plan.