Assuming a mortgage in Ontario: how it works

Summary: Assuming a mortgage means taking over a seller's existing loan, keeping its rate and remaining term, if the lender approves you. In Ontario it is generally available only on fixed-rate mortgages, and you still have to fund the seller's equity and pay land transfer tax on the full purchase price.

The appeal is obvious when a seller locked in a low rate a few years ago: inherit that rate and skip a fresh application. The catch is that assumption hinges on lender approval and a cash gap most buyers underestimate, so it is worth understanding before you firm up an offer.

Can you assume a mortgage in Ontario?

Yes, in principle. Assuming a mortgage means the buyer takes over the seller's remaining mortgage, including its rate, balance, and terms, instead of arranging a new loan. But it is never automatic, and not every mortgage qualifies. According to the Financial Consumer Agency of Canada, the assumable option is typically available on most fixed-rate mortgages and is not available on variable-rate mortgages or home equity lines of credit (HELOCs).

Before you count on assuming a seller's mortgage:

• Confirm the mortgage is assumable. Many conventional mortgages contain a "due-on-sale" clause that blocks assumption unless the lender agrees to waive it.

• Rule out variable and HELOC products. If the seller's financing is a variable-rate mortgage or a HELOC, assumption is generally off the table.

• Request the lender's assumption package early, and confirm it before you remove conditions, so a "no" doesn't surface after you're committed.

• Expect a lender fee. Most lenders charge an administrative fee to process an assumption.

How does lender approval and closing work?

This is the step buyers most underestimate: you cannot simply take over the seller's payments. The lender must approve you through a full assumption application (credit, income, and debt review), much like a new mortgage. Approval also matters for the seller: unless the lender formally releases them, the seller can remain liable for the loan if you later miss payments. A clean assumption gets the seller released.

From offer to keys, it usually runs like this:

1. Confirm assumability with the lender and request the assumption package.

2. Submit your qualification information for the lender's underwriting review.

3. Your lawyer requests the assumption statement and the exact outstanding balance for closing.

4. The assumed balance goes on the statement of adjustments, the ledger that sets what you owe on closing day.

5. Title transfers and the lender documents are registered to show you as the borrower going forward.

Lender approval timelines are the usual bottleneck, so they need to line up with your closing date — especially if you are coordinating a same-day buy-and-sell.

The equity gap: you still pay the seller

Assumption lets you take over the loan balance, but it does nothing about the equity the seller has built. That gap is yours to fund. If the purchase price is $900,000 and the assumed mortgage balance is $450,000, you take on the $450,000 loan but still owe the seller the other $450,000, which has to come from your down payment, a new second mortgage, or other financing.

So assumption is rarely a cost-elimination move. It is a rate-and-timing strategy, and if the seller's equity is large it can demand far more cash at closing than a conventional purchase. Map the whole picture, including the costs involved in a real estate transaction, before you commit.

How does assuming a mortgage change your land transfer tax?

It doesn't reduce it, which catches many buyers off guard. Ontario Land Transfer Tax (LTT) is calculated on the "value of the consideration," and the province includes the balance of any assumed mortgage in that figure. Assuming the loan instead of arranging new financing does not shrink the taxable amount.

On a $900,000 purchase where you assume a $450,000 mortgage, LTT is calculated on the full $900,000, not on the cash you bring to closing. In Toronto, the Municipal Land Transfer Tax (MLTT) applies on top of the provincial tax. You can model your numbers with our Ontario Land Transfer Tax calculator. And because assumption is typically a repeat-buyer move, the first-time buyer rebate usually won't apply, so the full LTT lands in your closing budget.

Assumption vs porting vs refinancing

These three get confused often, but they solve different problems:

In short: assumption makes sense when the seller's rate is genuinely better than what you'd get today, the lender will approve you within your closing window, and the equity gap is manageable.

Frequently asked questions

Is every mortgage assumable in Ontario?

No. Assumption is typically available only on fixed-rate mortgages; variable-rate mortgages and HELOCs generally can't be assumed. Even on a fixed-rate mortgage, a due-on-sale clause may block it unless the lender agrees, so confirm with the lender first.

Do I need the lender's approval to assume a mortgage?

Yes. The lender underwrites you as the new borrower (credit, income, debt) before allowing the assumption. Without that approval, the payment obligation can't transfer.

Does the seller stay on the hook after I assume their mortgage?

They can. In some cases the seller remains personally liable unless the lender formally releases them as part of approving you. A properly documented assumption with a release protects the seller.

Do I still pay land transfer tax if I assume the mortgage?

Yes, and on the full price. Ontario calculates LTT on total consideration, which includes the balance of the mortgage you assume — so assuming a loan does not lower the tax.

Is assuming a mortgage cheaper than getting a new one?

Not necessarily. You may keep a better rate, but you still fund the seller's equity, pay land transfer tax on the full price, and cover legal and lender fees. It is a rate strategy, not a way to avoid closing costs.

About the author

Joel Fox is a co-founder and COO at Ownright. He helps run the firm's day-to-day work on Ontario residential closings, refinances, and sales, and writes regularly to demystify the parts of a transaction that most homeowners only encounter once or twice in their lives.

At Ownright, we focus entirely on Ontario residential real estate law. On an assumption we coordinate the lender's documents, confirm the seller's release, fit the assumed balance into the statement of adjustments, and register the transfer — so the financing lines up cleanly at closing. You can start your closing online or get in touch with any questions.

Legal references: Land Transfer Tax Act, R.S.O. 1990, c. L.6 (consideration includes the balance of an assumed mortgage); Financial Consumer Agency of Canada guidance on assumable mortgages.

Important note: This article is not legal, financial, or tax advice. No one should act, or refrain from acting, based solely on the information in this post or any linked materials without first seeking appropriate legal or professional advice.