Borrowing to Invest? Most People Get the Tax Rule Backwards.

I am going to write about something most mortgage brokers avoid, and I am going to do it carefully, because the version of this idea that gets passed around at barbecues has a mistake in it that costs people real money.

The idea: your home has equity in it. Your mortgage rate is somewhere in the fours. If that equity could earn more than it costs to borrow, why is it sitting in the drywall?

It is a fair question. Here is the honest answer from the mortgage side of the desk - the part I am licensed for. The investing side belongs to your advisor, and I will say exactly where that line is.

How the borrowing actually works

There are two ways to pull equity out of a home you already own, and they behave differently.

1. A refinance. Replace your mortgage with a bigger one, up to 80% of the home's value, and take the difference as cash. Fixed structure, one payment, the cheapest rate of the two. The catch: doing it mid-term means a penalty to break your current mortgage. Doing it at renewal means no penalty at all - which is why renewal is the moment I bring this up with clients who have been thinking about it.
2. A home equity line of credit. Sits behind your mortgage, up to 65% of the home's value on the line portion, and you draw as you go. Higher rate than a mortgage, but you only pay interest on what you use, and you can pay it back and draw again. The full comparison is here.

Which one fits depends on how much, how fast, and whether you want the discipline of a fixed payment or the flexibility of a line. That is a fifteen-minute conversation.

The tax rule almost everyone gets backwards

Why this matters: the deduction is a big part of what makes the strategy work. Here is the difference on $100,000 borrowed at an illustrative 4.7%:

Same house, same $100,000, same rate. The account you put it in decides whether the investment needs to clear three percent or nearly five. People do this backwards constantly, because "TFSA" sounds like the tax-smart choice. For contributions from your paycheque, it is. For borrowed money, it is the opposite.

The arithmetic, honestly

Strip it down and the strategy is one comparison: what the money earns after tax and fees, versus what it costs after tax. I can tell you the right side of that equation to the dollar - the rate, the structure, the payment, the after-tax cost. I cannot tell you the left side. Nobody can promise it, and anyone who quotes you a return number as if it were a rate is doing something I would not do.

What I will tell you is what makes the right side of the equation bigger than people expect:

• Rates move. A variable-rate line follows prime. The Bank of Canada put a rate increase back on the table in its September 16 minutes. If your plan only works at today's rate, it is not a plan.
• The loan does not shrink when the market does. Borrow $100,000, watch the portfolio drop 20%, and you own $80,000 of investments and $100,000 of debt. The interest keeps coming either way.
• Fees are a rate too. A 2% management fee on borrowed money is a 2% hurdle before you have made a dollar.

Who this is actually for

I have watched this work, and I have watched it go wrong, and the difference was never the market. It was the person. It works for people with stable income, a long horizon, a payment they could carry even if the investment went to zero, and an advisor who built the plan with them and will be there when it is tested. It goes wrong for people who read a post like this, felt clever, and skipped the advisor.

If you are 55-plus and mortgage-free, this is a different conversation again, and the answer is often not a line of credit at all. That one is here.

The line I won't cross

I arrange the borrowing. I do not pick the investments, I do not forecast the returns, and I do not tell you whether to do this. I am not licensed to, and if a mortgage broker ever offers to do both from the same chair, that should make you nervous, not comfortable.

What I do: run the numbers on the borrowing side so you and your advisor are working with the real cost, not a guess. Structure it so the interest is deductible if that is the plan, which means keeping the borrowed money and the investment cleanly traceable - your accountant will thank you. And time it to your renewal if there is one coming, because that is the penalty-free moment.

The move for this week

If you have been turning this idea over: find out what your equity actually is and what it would cost to access. That part is free, takes fifteen minutes, and commits you to nothing. Take the number to your advisor. If the plan still makes sense with the real cost in it, I will build the borrowing side properly. If it does not, you found that out for free.