Second Mortgage vs HELOC vs Refinance: The Real Cost Comparison

You've got equity in your Ontario home and a reason to use it. A renovation. A tax bill. A kid's tuition. Debt you'd like to fold into one payment. The moment you start looking, three options show up, and they all sound roughly the same: second mortgage, HELOC, refinance.

They are not the same. And the difference that matters most isn't the interest rate on the brochure. It's a quieter question: do you keep the first mortgage you already have, or do you tear it up and start over?

That one decision drives everything else. Let's walk through it.

The one question underneath all three

Here's the thing. A refinance replaces your first mortgage. The other two sit behind it and leave it alone.

Why does that matter so much? Because a lot of people reading this signed a mortgage in 2020 or 2021 at somewhere around 1.5% to 2%. If that's you, your first mortgage is one of the most valuable things you own. Replacing it to access equity means giving up that rate on your entire balance, not just the new money you need.

So before you compare rates, sort your three options into two camps:

• Replace the first mortgage: refinance.
• Keep the first mortgage, add borrowing behind it: a home equity line of credit (HELOC) or a second mortgage that registers behind your existing loan.

Both of those "keep it" options rank behind your first mortgage in priority. That's what makes them second position, and it's why they price higher. The lender is further back in line if things ever go sideways.

What each option actually is

Refinance. You break your current mortgage and take out a new, larger one, up to 80% of your home's value (that's your LTV, how much you're borrowing against what the home is worth). The new loan pays off the old one and hands you the difference in cash. Lowest rate of the three, because it's a first mortgage. The catch: you re-qualify from scratch, you face the stress test, and if you're mid-term you may owe a break penalty.

HELOC. A revolving line secured against your home, sitting behind your first mortgage. You draw what you need, pay interest only on what you've used, and reuse it as you repay. Flexible and relatively cheap. But it's bank-issued, so you still have to qualify, including the stress test on the limit, and approval leans on your income and credit, not just your equity.

Second mortgage. A separate lump-sum loan registered in second position. Your first mortgage stays exactly where it is. Because these are often arranged through B or private lenders, they qualify mainly on your home equity rather than your income, they fund fast, and they carry a higher rate, quoted as a range with fees disclosed in writing. Terms are usually short, often one year, and frequently interest-only.

The comparison table

	Refinance	HELOC	Second Mortgage
Rate	Lowest (a first mortgage)	Low, usually prime-based	Higher; private seconds roughly 10–15%
Keeps your first mortgage?	No — it replaces it	Yes	Yes
Typical LTV limit	Up to 80% of value	Up to ~80% combined	Up to ~80–85% combined
Qualification	Full re-qualify + stress test	Bank qualify + stress test on limit	Mainly equity-based (B/private)
Speed	Slower (weeks)	Moderate	Fastest (days on many files)
Best used when	Your current rate is high and you want the cheapest cost of borrowing	You want ongoing, flexible access and you qualify at the bank	Your first mortgage is worth protecting, or you need speed / flexible qualifying

LTV and pricing here are typical, not guarantees. They move with the market and with your specific file.

A worked example: the 1.9% problem

Meet a homeowner in Hamilton. Home worth about $700,000. First mortgage of $400,000 at 1.9%, signed in 2021, with two years left on the term. They need $80,000 for a basement suite and to clear a line of credit.

Option one, refinance. To get the $80,000, they'd break the $400,000 mortgage and write a new one for $480,000 at today's rates, call it somewhere around 5%. That's not just a higher rate on the new $80,000. It's a higher rate on the whole $480,000. They'd also likely trigger a break penalty on the low-rate loan, and re-qualify the full amount under the stress test (the higher of your contract rate plus 2%, or 5.25%). Financially, this is the expensive path, even though the refinance rate is the lowest number on the page.

Option two, keep the 1.9% and add $80,000 behind it. A HELOC or second mortgage leaves the cheap first mortgage untouched. Yes, the new money costs more per dollar. But it's only $80,000 that carries the higher rate, not $480,000. On this file, that math wins clearly.

Between the two "keep it" choices: if this homeowner has strong income and clean credit, a HELOC is usually the cheaper draw. If their income is harder to document, their credit took a recent knock, or they need the money in days, a second mortgage priced on equity may be the realistic route, even at a higher rate, because it can actually close.

The rule of thumb: the lower your existing first-mortgage rate, the more it costs you to give it up. A 1.9% mortgage is worth defending. A 5.5% one, less so, at which point a refinance can genuinely be the cheapest answer.

When refinancing is the right call

None of this makes refinancing the villain. It's the cheapest option whenever you're not giving up a rate worth keeping.

Refinance tends to win when your current rate is already at or above market, when you're at renewal anyway (no penalty to break), when you want to consolidate a large amount at the lowest possible rate, or when you want one clean payment instead of two. Run your numbers on a refinance calculator first, and read our deeper guide on how mortgage refinancing works in Ontario before you commit to breaking a term.

A note on cost and who arranges these

Second mortgages, especially private ones, come with fees. Expect a lender fee and, where a brokerage arranges it, a brokerage fee, plus legal and appraisal costs of a few thousand dollars. All of it must be disclosed to you in writing before you sign. That's not fine print you chase down; it's your right.

Two consumer protections worth knowing. First, in Ontario a private mortgage may only be arranged by a Level 2 licensed mortgage agent or a mortgage broker, so you're always dealing with a licensed professional. Second, since January 1, 2025 the federal criminal interest rate is 35% APR, all-in, meaning interest and most fees together. On a small second mortgage, flat fees eat into that ceiling quickly, which is exactly why the fees have to be laid out clearly so you can see the true annualized cost.

The honest summary

Don't shop by the headline rate. Shop by what it costs you overall, and that starts with whether your first mortgage is worth protecting.

If it's a rock-bottom pandemic-era rate, keep it, and add borrowing behind it with a HELOC or a second mortgage. If it's an ordinary rate and you're near renewal, refinancing into one clean, low-rate loan is often the cheaper move. The best answer is the one that fits your actual file, not the one with the smallest number on the ad.

Frequently asked questions

Is a HELOC the same as a second mortgage?

They're cousins, not twins. Both sit behind your first mortgage. But a HELOC is a revolving line you draw and repay repeatedly, usually bank-issued and priced off prime, and it needs full qualification including the stress test. A second mortgage is typically a fixed lump sum, often arranged through a B or private lender, qualified mainly on your equity, and priced higher as a range with fees disclosed.

Why is a second mortgage rate higher than my first mortgage rate?

Position in line. If a home is ever sold to clear debts, the first mortgage gets paid first and the second lender is paid only from what's left. That extra risk is priced in. Private second mortgages in Ontario typically run in the range of roughly 10–15%, plus disclosed fees, and terms are usually short.

Does taking a second mortgage or HELOC affect my first mortgage rate?

No. That's the whole point of keeping it. Your first mortgage's rate, balance and term don't change. You're adding a separate loan behind it, which is why these options make sense when your first mortgage carries a rate you'd hate to lose.

Can I get a second mortgage with bruised credit or hard-to-prove income?

Often yes, because many second mortgages are underwritten primarily on home equity rather than credit score or income documents. That's the trade-off for the higher rate. A licensed mortgage agent can tell you whether a B lender or a private lender is the realistic fit for your file.

How do I decide between all three without guessing?

Start with the numbers. Compare the total cost of keeping your first mortgage and borrowing behind it against the total cost of refinancing the whole balance at today's rates, including any break penalty. A refinance calculator gets you a first read, and a licensed mortgage agent can price all three side by side so the cheapest real path is obvious.