Smith Manoeuvre Risks: What Nobody Tells You Before You Start

Most content about the Smith Manoeuvre focuses on the payoff: a tax deduction, a growing portfolio, debt that works in your favour. Fair enough — it's a legitimate strategy. But it carries real risk, and it deserves an honest accounting before you start, not after.

Variable-Rate Risk

The HELOC portion of a readvanceable mortgage almost always carries a variable rate. When rates rise, your carrying cost rises with it — and the tax deduction offsets some of that cost, but not all of it. Run the numbers assuming rates could be meaningfully higher than they are today, not just where they sit right now.

Leverage Risk

You're investing borrowed money. That amplifies gains, and it amplifies losses in exactly the same way. A market downturn hits differently when the money in it isn't fully yours — and unlike money you'd otherwise have sitting in cash, you can't simply wait it out without also carrying the debt cost.

CRA Traceability Risk

The entire deduction depends on a clean, documented paper trail proving the borrowed money was used to earn income. Mix investment borrowing with personal spending — even once, even by accident — and you risk losing the deduction on the whole balance, not just the tainted portion.

Behavioural Risk

Having a large, re-advancing line of credit available is its own kind of risk. It's easy for the line between "investment borrowing" and "emergency spending" to blur when the room is simply sitting there. This strategy rewards discipline more than it rewards optimism.

Liquidity Risk

If you're forced to sell investments during a downturn to cover cash-flow needs, you lock in losses on money that was never fully yours to begin with. The Smith Manoeuvre works best for people who won't be forced sellers.

Who Should Think Twice

If you don't have genuine investing discipline, if a variable-rate balance would cost you sleep, or if you're not confident you can keep borrowing purposes cleanly separated on paper — this strategy will cost you more than it gives back. It's not a shortcut, and it's not for everyone.