Why Five Basis Points Saves You $840 on a Refinance But Only $340 on a Purchase
A borrower in Nepean just paid $2,200 in legal and appraisal fees to switch her mortgage from 4.09% to 3.89%, cutting her rate by 20 basis points. She'll save roughly $840 per year on a $420,000 balance. Her neighbour, same income, same down payment, same lender, just closed on a purchase at 3.89% instead of 3.94%. His savings: $340 over the same year, on the same balance. Same rate drop, different transaction, wildly different math.
The difference isn't the rate. It's what you're paying to access it.
The Upfront Cost Asymmetry
When you buy, the lender charges you nothing to give you a mortgage. When you refinance, you pay to break the old contract. On a $420,000 balance at 4.09%, a three-month interest penalty runs about $4,200. Add legal fees, a new appraisal, and title insurance, and you're looking at $6,000 to $7,000 in total switching costs. The purchase borrower pays zero of this. Every dollar the refinance borrower saves has to climb out of that hole first.
At 5 basis points per year, a $420,000 mortgage saves roughly $210 annually (on an insured mortgage). Over a standard 5-year term, that's $1,050 in total savings, less than the cost of the appraisal alone. At 20 basis points, the same mortgage saves $840 per year, or $4,200 over five years, which starts to justify the $6,500 upfront cost. The purchase borrower, meanwhile, keeps the full $340 annual savings from a 5-basis-point drop because there was no penalty to offset.
The break-even threshold for a mid-term refinance usually sits around 40 to 50 basis points, depending on how far into the term you are and whether your penalty is calculated using the Interest Rate Differential (IRD) method. Under IRD, the penalty can exceed three months' interest if market rates have dropped sharply since you locked in. A borrower who signed at 5.25% in 2023 and tries to refinance in 2026 at 3.89% could face an IRD penalty north of $10,000 on a $500,000 mortgage.
The Qualification Math Flips
For a purchase, 5 basis points has a second-order effect through the mortgage stress test. Under OSFI rules, you qualify at the higher of your contract rate plus 200 basis points, or 5.25%. A buyer qualifying at 3.89% is tested at 5.89%. A buyer at 3.94% is tested at 5.94%. On a $90,000 household income, that 5-basis-point difference increases borrowing power by roughly $2,800. That rarely changes which house you can afford, but it occasionally closes a gap between your offer and the seller's ask.
For a refinance, the stress test still applies, but you're not trying to stretch into a bigger purchase. You already own the home. The qualification question is whether you can access enough equity to consolidate debt or fund renovations. A 5-basis-point drop might allow you to pull an extra $3,000 from your home, but if you're paying $6,500 to access it, the trade doesn't make sense.
When the Refinance Math Works
The refinance advantage appears when rates have moved significantly and you're early in your term. A borrower who locked in a 5-year fixed at 5.49% in late 2023 and refinances in mid-2026 at 3.89%, a 160-basis-point drop, saves roughly $6,700 annually on a $500,000 balance. Even with a $12,000 IRD penalty, the trade pays for itself in under two years. The remaining three years of the term are pure savings.
The second scenario where refinancing wins: you're at renewal. If your current term is ending, there's no penalty. A 5-basis-point improvement is free money. The decision becomes identical to the purchase case, except you already own the house and the lender already knows your payment history.
The purchase borrower, by contrast, extracts full value from every basis point immediately because the trade has no sunk cost. A 5-basis-point drop on a $420,000 mortgage at 3.89% (insured) means $340 less paid to the lender over the first year, with no fee to access it. That's $340 you keep, not $340 you spend to save $210 net.
Small rate moves create value. Whether you capture it depends on what you're paying to open the door.
A borrower in Nepean just paid $2,200 in legal and appraisal fees to switch her mortgage from 4.09% to 3.89%, cutting her rate by 20 basis points. She'll save roughly $840 per year on a $420,000 balance. Her neighbour, same income, same down payment, same lender, just closed on a purchase at 3.89% instead of 3.94%. His savings: $340 over the same year, on the same balance. Same rate drop, different transaction, wildly different math.
The difference isn't the rate. It's what you're paying to access it.
The Upfront Cost Asymmetry
When you buy, the lender charges you nothing to give you a mortgage. When you refinance, you pay to break the old contract. On a $420,000 balance at 4.09%, a three-month interest penalty runs about $4,200. Add legal fees, a new appraisal, and title insurance, and you're looking at $6,000 to $7,000 in total switching costs. The purchase borrower pays zero of this. Every dollar the refinance borrower saves has to climb out of that hole first.
At 5 basis points per year, a $420,000 mortgage saves roughly $210 annually (on an insured mortgage). Over a standard 5-year term, that's $1,050 in total savings, less than the cost of the appraisal alone. At 20 basis points, the same mortgage saves $840 per year, or $4,200 over five years, which starts to justify the $6,500 upfront cost. The purchase borrower, meanwhile, keeps the full $340 annual savings from a 5-basis-point drop because there was no penalty to offset.
The break-even threshold for a mid-term refinance usually sits around 40 to 50 basis points, depending on how far into the term you are and whether your penalty is calculated using the Interest Rate Differential (IRD) method. Under IRD, the penalty can exceed three months' interest if market rates have dropped sharply since you locked in. A borrower who signed at 5.25% in 2023 and tries to refinance in 2026 at 3.89% could face an IRD penalty north of $10,000 on a $500,000 mortgage.
The Qualification Math Flips
For a purchase, 5 basis points has a second-order effect through the mortgage stress test. Under OSFI rules, you qualify at the higher of your contract rate plus 200 basis points, or 5.25%. A buyer qualifying at 3.89% is tested at 5.89%. A buyer at 3.94% is tested at 5.94%. On a $90,000 household income, that 5-basis-point difference increases borrowing power by roughly $2,800. That rarely changes which house you can afford, but it occasionally closes a gap between your offer and the seller's ask.
For a refinance, the stress test still applies, but you're not trying to stretch into a bigger purchase. You already own the home. The qualification question is whether you can access enough equity to consolidate debt or fund renovations. A 5-basis-point drop might allow you to pull an extra $3,000 from your home, but if you're paying $6,500 to access it, the trade doesn't make sense.
When the Refinance Math Works
The refinance advantage appears when rates have moved significantly and you're early in your term. A borrower who locked in a 5-year fixed at 5.49% in late 2023 and refinances in mid-2026 at 3.89%, a 160-basis-point drop, saves roughly $6,700 annually on a $500,000 balance. Even with a $12,000 IRD penalty, the trade pays for itself in under two years. The remaining three years of the term are pure savings.
The second scenario where refinancing wins: you're at renewal. If your current term is ending, there's no penalty. A 5-basis-point improvement is free money. The decision becomes identical to the purchase case, except you already own the house and the lender already knows your payment history.
The purchase borrower, by contrast, extracts full value from every basis point immediately because the trade has no sunk cost. A 5-basis-point drop on a $420,000 mortgage at 3.89% (insured) means $340 less paid to the lender over the first year, with no fee to access it. That's $340 you keep, not $340 you spend to save $210 net.
Small rate moves create value. Whether you capture it depends on what you're paying to open the door.
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