Common mortgage mistakes I see
Ten patterns that show up on Canadian mortgage files at every stage. The mistake, what it costs on a typical file, and the fix. None of these are hard to avoid once you know to look for them.
Most of these mistakes don't happen because the borrower is uninformed. They happen because nobody asked the right question at the right moment.
Before signing
Rate-shopping a 5-year fixed without checking the IRD method.
What it costs. On a $400,000 fixed mortgage with 24 months remaining, the same break can cost $5,500, $8,000, or $12,000+ depending on whether the lender uses 3-month interest, discounted-rate IRD, or posted-rate IRD. Most clients only learn which one applies when they need to break.
The fix. Ask before signing: “What's the IRD calculation method on this product?” Big banks typically use posted-rate IRD; monolines and credit unions typically use discounted-rate IRD. For files where mid-term flexibility matters, that's a decision criterion, not a footnote.
Skipping the prepayment privilege question.
What it costs. Standard prepayment privileges are 15% of original principal per year plus a 15-20% payment increase. The clients who don't ask end up with sub-standard limits they didn't know to compare. On a $500,000 mortgage, the difference between a 10% and 20% prepayment privilege is $50,000 of optionality per year.
The fix. Ask the broker to spell out the lump-sum privilege, the payment increase privilege, and any timing restrictions (anniversary-only vs anytime). Then ask which lenders in your file's lane have stronger or weaker privileges.
Buying without modeling the second deal.
What it costs. The structure of THIS mortgage caps your future qualifying capacity. A 25-year amortization, a non-readvanceable product, or a rate-shopped 5-year fixed locks you into options for the next 5 years. Most clients don't realize this until they're trying to qualify for the second property and the first file is the constraint.
The fix. Before signing, ask: “If I'm planning to fund a build or buy a second property in 2 to 3 years, what's the optimal structure for THIS mortgage?” A broker thinking two deals ahead will surface trade-offs unprompted. Strategy framework: Questions to Ask Any Mortgage Broker.
During the term
Staying on monthly when accelerated bi-weekly would save 3-5 years.
What it costs. On a typical Ontario mortgage, switching from monthly to accelerated bi-weekly takes 3 to 5 years off the amortization with no rate change, no product change, no behaviour change. The total cost of NOT switching is tens of thousands in extra interest over the life of the mortgage.
The fix. Call the lender, ask for accelerated bi-weekly. Confirm the per-payment amount is exactly your monthly payment divided by two (not your annual cost divided by 26, which is plain bi-weekly with no acceleration). Strategy: Accelerated Payment Frequency. Math: Mortgage Payment Calculator.
Treating the readvanceable HELOC as accessible spending money.
What it costs. The whole point of a readvanceable mortgage is that the HELOC sub-account grows automatically as principal pays down, ready to deploy on a strategy when the time comes. Drawing from it for vacations, renovations, or to bridge cash flow gaps wastes the optionality. By the time you actually want to layer Cash Damming or Investment Leverage, the HELOC is half-tapped on personal-use debt that's not deductible.
The fix. Treat the HELOC sub-account as restricted, not as spending money. If you need access to liquidity, that's a separate HELOC. Strategy: Readvanceable Mortgage Setup.
At renewal
Signing the renewal letter as-is to avoid the friction.
What it costs. The renewal rate from your existing lender is almost always above the rate they'd offer to win you back from another lender. The cost of clicking accept on the renewal letter is typically 0.25 to 0.50% in rate, which on a $475,000 mortgage is $1,200 to $2,500 a year of extra interest. That's on the easy version of this mistake. The harder version is missing the chance to restructure (readvanceable, cash damming, debt consolidation) at the cheapest possible moment.
The fix. Start the renewal conversation 90 to 120 days out. Compare the letter against current market and against a structural change. The Renewal Decision Engine walks through the five paths.
Switching lenders for rate without checking the new IRD method.
What it costs. You break the existing term (paying the old IRD) to switch to a slightly better rate at a new lender. If the new lender uses posted-rate IRD, you've traded one harsh penalty for another. The next time you need to break (refi for a build, change products), the new IRD penalty can swamp years of rate savings.
The fix. Confirm the new lender's IRD calculation method before signing. If you're moving from a big bank to another big bank for a 0.20% rate spread, you may not be ahead. Monolines and credit unions typically have softer IRD math.
When refinancing
Cash-out refi without addressing the spending pattern that built the debt.
What it costs. The math on a cash-out refi is straightforward: roll high-interest consumer debt into the mortgage at a much lower blended rate, free up cash flow. The failure mode is also straightforward: people consolidate the cards, run them right back up, and end up two years later with the bigger mortgage AND the same consumer debt on top. That's worse than the starting point.
The fix. Treat the consolidation as the back half of a budget rebuild, not a one-step fix. Close most of the cards the same week the refi funds. Set the new mortgage to accelerated bi-weekly. Use the freed cash flow as a head start on paydown, not as a raise. Full strategy: Cash-Out Refinance / Debt Consolidation.
Investment leverage without clean tracing.
What it costs. The Investment Leverage Strategy converts non-deductible mortgage interest into tax-deductible investment-loan interest. The math compounds beautifully over 15 years. The deduction depends on a CRA-defensible chain: dollar borrowed equals dollar invested, dedicated account, no co-mingling. One personal charge run through the investment HELOC contaminates the deduction for that period and creates an audit reconstruction problem. The cost of bad tracing isn't the lost deduction in one year; it's the credibility hit on the entire structure.
The fix. Set up dedicated accounts before you draw the first dollar. Document every transaction in a way that survives a CRA review. Run the strategy past a CPA who can review your specific T776 history. Full strategy: Investment Leverage Strategy. Glossary detail: ITA 20(1)(c).
Extending amortization with no plan for the freed cash flow.
What it costs. Refinancing to a 30-year amortization (where the file qualifies) lowers monthly payment but adds total interest over the life of the loan. The trade is positive only if the freed cash flow goes to a productive use: paying down higher-interest debt, building a HELOC reserve, layering investment debt, funding a build. The trade is negative if the freed cash flow disappears into lifestyle creep.
The fix. Decide what the freed cash flow is for before extending. Set the redirect on autopilot (automatic extra principal payment, automatic transfer to savings, automatic investment contribution). If you can't name where the freed dollars go, the extension is a bad trade.
Want to check your file against this list?
About 30 minutes, on the phone or video. Bring your renewal letter or your current rate sheet if you have one. The mistakes on this list are the ones that get caught on a strategy call most often.
Book a strategy call