Buying With a Roommate or Partner: Splitting a Mortgage vs. Splitting Rent

Key takeaways

• Lenders combine both applicants’ incomes and both applicants’ debts. A partner’s car loan reduces what you jointly qualify for.
• Everyone on the mortgage is liable for the whole payment. If one person stops paying, the lender pursues the other for all of it.
• How you hold title — joint tenancy or tenants in common — decides what happens to a share on death, and they behave very differently.
• A missed payment damages both credit files, regardless of whose turn it was.
• Get a co-ownership agreement drafted by an Alberta real estate lawyer before you write an offer. It is cheap in advance and expensive to improvise later.

Who this guide is for

Two people in Edmonton — partners, siblings, friends — currently splitting rent and considering whether to split a mortgage instead, including unmarried couples who do not have the default legal protections that marriage supplies.

What changes when you buy together

• Qualifying power. Lenders assess the combined application, so two moderate incomes routinely reach a home neither would qualify for alone.
• Combined debts. The other side of the same coin. Both applicants’ obligations count toward the total debt service ratio capped near 44% under CMHC guidelines, so one person’s car payment lowers what both can borrow.
• Joint liability. This is the one people underestimate. The lender did not agree to your 50/50 arrangement; it holds each of you responsible for the full amount.
• Credit, shared. The mortgage appears on both files. Paid on time it helps both; missed, it damages both.

Joint tenancy vs. tenants in common

These are the two ways to hold title in Alberta and the difference matters more than the names suggest.

• Joint tenancy carries a right of survivorship: if one owner dies, their interest passes automatically to the survivor, outside the will. Common between spouses.
• Tenants in common gives each owner a distinct share — which can be unequal, reflecting unequal down payments — and that share passes by the owner’s will rather than to the co-owner. Usually the better fit for friends, siblings, or partners contributing different amounts.

Choosing between them is a legal decision with estate consequences, and it is made when the transfer is registered. An Alberta real estate lawyer should walk you through it before closing rather than after.

The conversation to have before you shop

A lender only cares that the mortgage is paid; it has no opinion about your private arrangement. That makes the private arrangement entirely your responsibility to define. Settle in writing:

• Who contributed what to the down payment, and whether that buys an unequal share of the title.
• How the mortgage, property tax, insurance, utilities and maintenance are split month to month.
• What happens if one person wants out — a right of first refusal for the other, a valuation method, and a timeline.
• What happens if one person cannot pay, temporarily or permanently.
• What happens on death, disability, or a relationship ending.

Getting out later is the hard part

A lease ends by itself. A mortgage does not. Removing one person from a mortgage generally requires the remaining owner to requalify alone — on their income, at the stress-test rate of the greater of contract plus 2% or 5.25% — or the property to be sold. If the remaining owner cannot requalify, selling may be the only option, on someone else’s timetable.

None of this is a reason not to buy together. It is a reason to write down the exit before you need it.

Sources

• Government of Alberta — Land Titles
• CMHC — Calculating GDS / TDS
• Financial Consumer Agency of Canada — Preparing to get a mortgage

Frequently asked questions