Assuming a Mortgage in Ontario: A Buyer and Seller Guide

When interest rates are high, a seller's older, lower-rate mortgage can look very attractive to a buyer. Mortgage assumption — where the buyer steps into the seller's mortgage and takes over the remaining payments — is one way to access that rate. But assumption is not simply a paperwork swap. It requires lender approval, has real legal consequences for both parties, and may not be available at all depending on the mortgage contract.

This guide explains how mortgage assumption works in Ontario, what each party needs to know, and what can go wrong if the process is not handled properly.

What Is a Mortgage Assumption?

When a mortgage is assumed, the buyer (the new owner) takes on personal liability for the mortgage debt that was originally owed by the seller. The key point: the mortgage stays on title and the buyer agrees to make payments going forward, under the same terms (rate, remaining amortization, payment amount) that the seller originally negotiated.

From the lender's perspective, assumption means approving a new borrower for an existing loan.

Is Your Mortgage Assumable?

Not all mortgages can be assumed. Whether assumption is allowed depends entirely on the mortgage contract:

• Open mortgages are almost always fully prepayable and technically can be assumed, but there is little financial incentive to assume an open mortgage (you could just get your own).
• Closed mortgages — the most common type — often include an "assumption with lender consent" clause. The buyer can assume the mortgage, but the lender must approve the new borrower and may charge an assumption fee.
• Some older mortgage contracts are fully assumable without lender approval (sometimes called "freely assumable"), but these are rare in modern lending.
• Some contracts contain a due-on-sale clause: if the property is sold, the full mortgage balance becomes immediately due. These are less common in Canada than in some other jurisdictions, but they do exist in some private mortgage contracts.

Step one for any buyer or seller considering assumption: read the existing mortgage contract carefully, or ask your lawyer to review it.

The Lender Approval Process

Assuming the contract allows assumption with consent, the buyer must apply to the existing lender for approval. This typically involves:

1. Full credit and income review — the same (or similar) process as applying for a new mortgage. The lender wants to confirm the buyer can service the debt.
2. Property appraisal — the lender confirms the property value supports the outstanding mortgage balance.
3. Assumption agreement — both the seller and buyer sign documents acknowledging the transfer of obligation.
4. Assumption fee — lenders typically charge a fee to process the assumption. Verify the current amount with the specific lender, as fees vary.

The lender is not obligated to approve the assumption. If the buyer's creditworthiness does not meet the lender's current standards, assumption will be declined.

The Critical Risk for Sellers: Ongoing Liability

This is the part sellers most often overlook. When a buyer assumes your mortgage, you may remain on the hook for the debt unless the lender formally releases you.

A lender release of the seller is called a covenant discharge or a release of personal covenant. Without it, if the buyer defaults on the mortgage and the lender's recovery from the property falls short, the lender may come after the original borrower (the seller) for the deficiency.

Some lenders grant this release automatically as part of the assumption process. Others do not. Sellers must explicitly ask: "Will you release me from personal liability under the mortgage covenant upon assumption?" Get the answer in writing before agreeing to allow an assumption.

If the lender refuses to release the seller, the seller is essentially co-signing for the buyer's mortgage — with no ongoing benefit and full financial exposure. Most sellers in that position should reconsider allowing the assumption.

What Happens to the Mortgage Gap?

Unless the purchase price exactly equals the outstanding mortgage balance (rare), there will be a gap that the buyer must bridge:

• Purchase price > Mortgage balance: The buyer needs additional funds — either cash, a second mortgage, or a new top-up loan — to make up the difference between the assumed mortgage and the total purchase price.
• Purchase price < Mortgage balance: The seller must pay down the mortgage to the purchase price level at closing. This can trigger prepayment considerations under the mortgage contract.

Both scenarios require careful financial planning before the offer is structured.

How Assumption Affects the Offer to Purchase

If the parties agree to a mortgage assumption, the Agreement of Purchase and Sale should specifically address:

• That the sale is conditional on lender approval of the assumption
• The terms of the assumed mortgage (rate, balance, remaining term)
• The allocation of any assumption fee
• Whether the seller is requiring a release of personal covenant as a condition

Failing to address these points can lead to disputes if the lender declines the assumption or refuses to release the seller.

Frequently asked questions