Co-Ownership Agreements for Ontario Property

When two or more people buy property together in Ontario, the deed registers them under one of two ownership structures. Joint tenancy gives each owner an equal, undivided interest in the whole property, along with a right of survivorship — meaning that when one joint tenant dies, their share generally passes automatically to the surviving joint tenant(s), bypassing their estate and will entirely.

Tenancy in common works differently. Each co-owner holds a distinct share — which doesn’t have to be equal — that forms part of their own estate when they die, and can be sold, mortgaged, or willed independently of the other owners. Friends, family members, and investors buying together often choose tenancy in common precisely because it allows unequal contributions and independent estate planning.

Choosing between the two is an important decision with real legal consequences, but it is only half the picture. Neither structure, by itself, says anything about how the owners will actually share expenses, use the property, or handle a disagreement.

It is possible, and fairly common, to change how title is held after a property has already been purchased, though doing so generally has legal and tax implications worth understanding first. People sometimes assume the ownership structure on title is a complete description of their arrangement with their co-owner, when in reality it is simply the mechanism for recording who owns what and what happens to a share on death — nothing more.

The deed answers a narrow legal question: who owns what share, and what happens to that share on death. It does not answer the questions that actually come up in day-to-day co-ownership — who pays the mortgage, property tax, insurance, and repairs, and in what proportion; who gets to use the property and when, if it’s a shared recreational property or an investment unit; how decisions about renovations, refinancing, or selling get made; and what happens if one owner’s circumstances change.

A co-ownership agreement is a separate, private contract between the owners that fills in these gaps. It sits alongside the deed rather than replacing it, and it is generally the document people actually need to consult once a disagreement arises.

The specific terms vary with the relationship and the property, but recurring elements include how ownership percentages were determined (equal shares, or proportional to each person’s down payment and ongoing contributions); how ongoing expenses are split and collected, including what happens if a cost estimate turns out to be wrong; and how major decisions — a renovation, refinancing, taking on a tenant, or selling — get made, whether by unanimous agreement, majority vote weighted by ownership share, or some other process.

A well-drafted agreement also typically addresses use of the property, which matters most for shared recreational or multi-unit properties where more than one owner might want to use or live in the space at the same time; record-keeping for shared expenses, to avoid disputes over who paid what; and a dispute resolution process, such as mediation, before anyone heads to court.

For co-owned properties purchased with a mortgage, the agreement may also cross-reference obligations under the mortgage itself and any condominium rules if the property is a condo unit — in that case, understanding the condominium corporation’s own governing documents, discussed in our guide to status certificates, is a related but separate step.

Many co-owners also find it useful to set out a reserve fund arrangement — a shared account each owner contributes to, used to cover unexpected repairs or shortfalls without needing to negotiate a special contribution every time something comes up. This kind of practical, upfront planning tends to prevent exactly the sort of small disagreements that can otherwise snowball into a larger dispute between co-owners over time.

One of the most valuable things a co-ownership agreement can include is a pre-agreed process for what happens when one owner wants out — whether because of a life change, a falling-out, or simply a shift in financial priorities. Without this, the remaining owners and the departing owner are left to negotiate from scratch, often at a moment when the relationship is already strained.

Common mechanisms include a right of first refusal, giving the remaining owners the first opportunity to buy out a departing owner’s share before it’s offered elsewhere; an agreed valuation method, such as an independent appraisal, to avoid disputes over price; and a defined timeline for the buyout to be completed, including how financing for the buyout will be arranged.

Addressing exit planning up front doesn’t assume the relationship will fail — it simply recognizes that circumstances change, and that having a clear process reduces the chance that a change in one owner’s life becomes a legal battle for everyone involved.

It can also help to address what happens if a co-owner wants to bring in someone new — for example, selling their share to a third party rather than to the existing co-owners. Many agreements restrict this, or require the other owners’ consent, precisely because co-ownership often depends on a working relationship between the specific people involved, not just on the underlying asset.

A common and difficult scenario is a co-owner who stops contributing to the mortgage, taxes, or other shared expenses. Without an agreement addressing this directly, the other owners generally have to choose between covering the shortfall themselves — to avoid mortgage default or tax arrears affecting everyone’s interest in the property — or risking the consequences of letting the shortfall go unpaid.

A co-ownership agreement can set out consequences for missed contributions in advance, such as interest on the amount advanced by other owners, an adjustment to ownership shares reflecting unequal contributions over time, or a defined process for addressing a persistent default, including a forced buyout. Having this spelled out before a problem arises generally produces a far more predictable outcome than negotiating it for the first time in the middle of a dispute.

When co-owners cannot agree — on a buyout, a sale, or anything else — and there is no agreement to fall back on, Ontario law provides a court remedy called partition and sale under the province’s Partition Act. A co-owner can apply to the court, which can order the property divided (rarely practical for a single house) or, far more commonly, sold, with the proceeds distributed according to each owner’s share.

Partition and sale is a genuine legal right available to co-owners, and courts have historically been reluctant to refuse it outright except in limited circumstances. But it is generally slower, more expensive, and less predictable than resolving the same question through a pre-agreed mechanism — legal costs, delay, and the uncertainty of a forced sale process are all real downsides compared to an orderly buyout under an existing agreement.

This is general information about how co-ownership and partition and sale typically work under Ontario law, not an assessment of any specific property or relationship. Anyone contemplating a shared purchase, or already in one without a written agreement, may find it useful to review our guide to the Agreement of Purchase and Sale and our tools and checklists section, or to reach out through our contact page with general questions.