Michael sold $85,000 of his non-registered portfolio in March to pay down his mortgage, then re-borrowed the same amount through his HELOC to buy dividend stocks. The idea: convert non-deductible mortgage debt into tax-deductible investment debt. He expected to save roughly $2,900 a year in taxes at his 34% marginal rate on $8,500 of annual interest.

What he didn't expect: a $12,600 capital gains tax bill and $340 in brokerage commissions. His accountant walked him through it in April. Michael had bought most of the liquidated positions between 2018 and 2020. The adjusted cost base was $52,000. The $33,000 gain triggered $6,600 in federal tax (50% inclusion rate, 20% federal rate) and roughly $6,000 in provincial tax. Add the commissions and he was out $12,940 before he claimed his first interest deduction.

At $2,900 in annual tax savings, the break-even point is 4.5 years. That's assuming the HELOC rate stays at 7%, the investments yield enough to justify the debt, and Michael doesn't sell the new positions early.

The debt swap math looks clean when you ignore the transaction friction. Borrow to invest, deduct the interest, compound the tax refund. The structure works. What breaks it is the cost of getting into the structure.

Where the Tax Hit Comes From

Capital gains tax applies the moment you sell. If you bought an ETF at $60 and it's now worth $110, you're carrying $50 of deferred gain per share. Selling to fund the debt swap crystallizes that gain immediately. For individuals, 50% of the gain is taxable income. On $50,000 of realized gains, $25,000 gets added to your income for the year. At a 40% marginal rate, that's $10,000 to CRA.

The tax deduction on the new debt accrues annually. If you borrow $85,000 at 7% and your marginal rate is 34%, the deduction saves you roughly $2,000 a year. The tax hit is upfront and full. The savings are delayed and incremental.

Transaction costs stack on top. Mutual funds with deferred sales charges can carry exit penalties of 3-5% if you're still inside the redemption schedule. ETFs and stocks incur commissions. Even at $10 per trade, liquidating a dozen positions costs $120.

When the Swap Still Works

Three conditions make the upfront cost tolerable.

First, a high adjusted cost base. If you bought the assets recently or at prices near today's value, the deferred gain is small. Selling $100,000 of positions with a $95,000 ACB triggers $2,500 in taxable income. At a 45% rate, that's $1,125 in tax. One year of interest deductions covers it.

Second, capital loss carryforwards. If you have $30,000 of net capital losses from previous years, you can sell $60,000 of gains tax-free. The carryforward offsets the inclusion, and the entire transaction cost is just commissions.

Third, a long holding period with no intention to sell the new investments. If you're certain the debt will stay in place for a decade, the annual tax savings compound well past the initial friction. A $10,000 upfront cost paid back over ten years at $2,500 a year nets $15,000.

Where it fails is when the portfolio has large embedded gains, no offsetting losses, and the investor exits the strategy within five years.

The Recoup Horizon

Calculate the total upfront cost: taxes plus commissions. Divide by the annual tax savings from the interest deduction. That's your break-even in years.

If the number is above seven, the swap is speculative. Market returns over seven years are wide. HELOC rates might rise. The investment might underperform. You're betting a lot of variables hold.

If it's under three, the friction is manageable. The deduction recoups the cost fast enough that normal variance won't kill the strategy.

Michael's 4.5 years sits in the middle. Not obviously wrong, but not obviously right either. He's locked into the structure until 2030 to break even. If rates spike or the dividend yield compresses, he's underwater.