Short answer
Adding someone to an existing mortgage isn’t a simple addition: the lender requalifies the mortgage with both of you, the legal title usually changes too, and the transfer can trigger land transfer tax. It makes both people liable for the whole debt, and removing someone later is harder than adding them. This page covers adding a person after you’ve bought; buying together from the start is covered in co-signing a mortgage and joint mortgages. It is one of our guides to lenders, brokers and special situations.
Why People Add Someone to a Mortgage
| Reason | Notes |
|---|---|
| Combine incomes to qualify for a larger mortgage or a refinance | The lender counts both incomes (see qualifying for a larger mortgage) |
| Add a spouse or partner after purchase | Often done following marriage or common-law status |
| Add an adult child to assist aging parents | Helps parents maintain the property or qualify for refinance |
| Build a co-borrower’s credit history | The mortgage then appears on both credit reports |
Step 1: Get Lender Approval
You cannot add someone to your mortgage unilaterally. You must apply through your lender:
| Step | What happens |
|---|---|
| Submit application | Both borrowers apply as if it were a new mortgage |
| Full underwriting | Lender reviews credit, income and debts for both (see the underwriting process) |
| Stress test applied | You qualify at the greater of your contract rate plus 2% or 5.25%. |
| Mortgage amendment issued | If approved, lender creates a legal amendment |
| Legal work required | A real estate lawyer prepares the title transfer and mortgage documentation |
Costs: legal fees for the title change and mortgage amendment, any land transfer tax (below), and an appraisal if the lender requires one.
Step 2: Understand Land Transfer Tax Risk
When you add someone to the title (which most lenders require alongside the mortgage), you transfer a share of the property to them, and that can trigger land transfer tax on the value of the share. Some transfers, such as certain transfers between spouses, may be exempt under provincial rules, so confirm with your lawyer or the provincial guidance before you proceed; each province’s tax and exemptions are on our land transfer tax pages.
| Province | Land transfer tax on title addition? | Notes |
|---|---|---|
| Ontario | Can apply, on the value of the interest transferred | Toronto adds a municipal land transfer tax (Ontario, Toronto) |
| British Columbia | Can apply, on the value of the interest transferred | See BC property transfer tax |
| Alberta | No land transfer tax | Land titles registration fees apply (Alberta) |
| Quebec | Can apply (the “welcome tax”) | See Quebec’s welcome tax |
| Other provinces | Varies | See the provincial pages |
Step 3: Joint Tenancy vs Tenancy in Common
When the title is updated, you must decide how the ownership is structured:
| Ownership type | How it works | Right of survivorship |
|---|---|---|
| Joint tenancy | Each owner holds an undivided interest equally | Yes: on death, the interest passes automatically to the surviving owner(s) |
| Tenancy in common | Each owner holds a specified percentage | No: on death, the interest goes to the estate under the will |
Couples often choose joint tenancy for the survivorship benefit. Partners with different ownership shares or estate planning needs typically prefer tenancy in common.
Step 4: Legal Agreement for Non-Spouses
When the person added isn’t a spouse (a parent, sibling or business partner), a written co-ownership agreement usually covers:
| Item to address in agreement | Why |
|---|---|
| Each party’s financial contribution and ownership percentage | Prevents disputes if one party contributes more |
| Who pays mortgage, taxes, insurance, maintenance | Defines ongoing obligations |
| What happens if one party wants to sell | Buyout rights, forced sale |
| What happens on death of one co-owner | Survivorship or estate distribution |
| What happens on relationship breakdown | Process for resolving the shared asset |
A real estate lawyer can draft one; without it, a dispute over the property can end up in court. How co-owners structure this is covered in co-ownership mortgages.
Step 5: Removing Someone Later
Adding is easier than removing. Removal (assumption) requires:
| Step | Details |
|---|---|
| Remaining borrower requalifies alone | At the current qualifying rate |
| Lender approval | Not guaranteed; it can be declined if the remaining borrower doesn’t qualify alone |
| Title updated by a lawyer | Legal fees again, and possibly land transfer tax |
| Potential discharge and reinstatement | Depending on lender and timing |
In a separation, if neither person can buy the other out and qualify alone, the home often has to be sold; see a mortgage after divorce.
Before You Add Someone to Your Mortgage: Checklist
- Lender contacted and process confirmed (approval is not automatic)
- Both borrowers’ credit, income, and debts reviewed together
- Stress test qualification confirmed with combined financials
- Land transfer tax cost estimated for your province
- Decision made on joint tenancy vs tenancy in common
- Co-ownership agreement drafted (for non-spousal co-borrowers)
- Real estate lawyer retained for title and mortgage amendment
- Implications of future removal or separation considered
- Impact on each borrower’s TDS ratio and future borrowing capacity confirmed
Bottom Line
Adding someone to your mortgage makes both people fully liable for the debt, means requalifying together, and changes the title in a way that can cost land transfer tax. It is a legal and financial step usually done with a real estate lawyer and a written agreement on what happens if the arrangement ends. If the goal is a better rate on the combined mortgage, see how to negotiate your mortgage rate.
Related Reading
- Before You Break Your Mortgage in Canada: What It Will Cost You
- Before You Quit Your Job: Financial Checklist Canada
→ Back to: Complete Canadian Mortgage Guide
Sources
The figures and rules on this page come from these sources, last checked against them on September 29, 2026. How we check facts.