A co-ownership agreement in Ontario is a private contract between the people buying a property together that spells out ownership shares, how costs get split, and what happens if someone wants out, sitting alongside and separate from the registered title-holding decision itself. If you’re buying with a friend, a sibling, an unmarried partner, or a co-investor rather than as a married couple, this is the document that does the actual preventive work, because none of you get a married spouse’s automatic protections if things go sideways later. This guide covers what it should actually contain, not a template to fill in. For the rest of what goes into buying together in Toronto, see our complete Toronto real estate guide or browse the rest of our guides.
What a co-ownership agreement actually is
A co-ownership agreement is a private contract between the co-owners themselves. It’s separate from, and sits alongside, the decision of how title gets held, which is its own question of whether you hold as joint tenants or tenants in common, covered in full in our guide to joint tenancy versus tenants in common in Ontario. Ontario’s own guidance on developing a legal contract for co-ownership describes it as the document that clarifies each owner’s rights and obligations and protects everyone if a dispute comes up later, and the province recommends getting proper legal advice to prepare one rather than working from a generic form.
Ontario’s own guidance names five areas a co-ownership agreement should cover: the ownership structure itself, how decisions get made, rules for using the property, how finances and insurance work, and how upkeep responsibilities and any misconduct get handled. The sections below walk through what actually goes into each of those, in the order that tends to matter most to people buying together for the first time.
Ownership shares and contributions
Ownership doesn’t have to be split evenly, and in practice it often isn’t, especially where one buyer is putting in more of the down payment or carrying more of the ongoing cost. A tenants in common arrangement can hold any split of shares the co-owners agree to, unlike joint tenancy, which requires equal shares; the mechanics of each title form are covered in full in our guide above rather than repeated here. What this agreement should do is record the actual numbers in writing: who contributed what to the down payment, in what proportion each person owns the property, and how that ownership percentage was calculated, so there’s a written record rather than a verbal understanding everyone remembers slightly differently a few years later.
An unequal split changes what the rest of the agreement needs to say. A Toronto real estate law firm’s own guidance on whether you need a co-ownership agreement notes that a lopsided arrangement, a 75/25 split rather than an even 50/50 one, typically needs the larger owner to have more say over major decisions, and needs the smaller owner to have a workable exit path, since a buy-out mechanism built for equal partners doesn’t automatically work when one side can’t realistically afford to buy the other out at the full price. Naming the actual split and tying the rest of the agreement’s mechanics to it, rather than assuming an even partnership, is what makes an unequal arrangement hold up when it’s tested.
Ongoing cost-sharing, and what happens if someone falls behind
Beyond the down payment, Ontario’s own guidance specifically names mortgage payments, property tax, operating expenses, major repairs, and insurance as the categories a co-ownership agreement should address directly. For a condo, add condo fees and any special assessments to that list. The agreement should state how each of those gets split, whether that matches the ownership percentage exactly or follows a different arrangement the co-owners have agreed to, and how the money actually moves: a shared account each owner contributes to on a schedule is common, with a clear record of who paid what and when.
Decide what happens when one owner falls behind before it happens, not after. A workable agreement usually sets a short cure period for a missed contribution, followed by a defined remedy if it isn’t fixed, commonly the other owner covering the gap and being owed that amount back, sometimes with interest, with a repeated or serious shortfall eventually becoming grounds to force a resolution under the agreement’s own exit terms. There’s no single required formula here, but leaving the question unanswered means the first missed payment becomes a negotiation from scratch, at exactly the moment the co-owners are least likely to agree calmly on anything.
Exit and buy-out mechanics
This is usually the section that matters most and gets written the least carefully. At minimum, the agreement should give a co-owner who wants out a defined path to sell their share, commonly a right of first refusal for the remaining owner or owners before the share can be offered to anyone outside the group, along with a method for actually pricing it, whether that’s an independent appraisal, a formula, or an agreed process for picking one.
A more complete agreement adds a buy-sell mechanism for when the owners can’t agree on price or timing, most commonly a shotgun clause: one owner names a price for their share, and the other must either buy at that price or sell their own share at the identical price. It forces both sides to name a number they’d actually accept on either side of the deal, which tends to produce a fairer figure than either side simply naming their own preferred price. Our guide to the Partition Act in Ontario covers what happens by default, through the courts, when co-owners have no agreement at all and can’t resolve a forced sale themselves; a buy-sell clause in a co-ownership agreement exists specifically to avoid ever needing that court process.
A buy-sell clause settles a deadlock privately. Without one, a deadlocked owner falls back to the Partition Act’s own court process.
What happens on an owner’s death
This depends entirely on the title-holding form chosen, not on the co-ownership agreement itself. Under joint tenancy, the right of survivorship means a deceased owner’s share passes automatically to the surviving co-owner or co-owners, outside the estate and outside a will entirely. Under tenants in common, a deceased owner’s share instead passes through their own estate, according to their will or, if there isn’t one, the intestacy rules that apply. Our guide to joint tenancy versus tenants in common in Ontario covers that distinction fully, and our guide to survivorship applications in Ontario covers what the surviving owner actually has to do to update title after a joint tenant dies. A co-ownership agreement can still usefully address what happens to the practical, ongoing obligations, who keeps covering the mortgage and expenses while an estate is settled, for example, but it doesn’t override which title form decides where the ownership share itself actually goes.
Why this matters specifically for a non-married co-purchase
Married spouses get a set of automatic protections under the Family Law Act over a matrimonial home, regardless of whose name is actually on title. A common-law partner, a dating partner, a sibling, a friend, or a co-investor gets none of that automatically. Our guide to common-law property rights in Ontario covers the fuller legal picture of what a common-law partner can and can’t claim without being on title, including the unjust enrichment and constructive trust routes that exist for exactly this gap.
That gap is exactly why a co-ownership agreement matters more, not less, for people who aren’t a married couple. Nobody is relying on a marital-property regime to sort out who owns what if the relationship or the arrangement ends. The agreement is the thing doing that job instead, and it deserves the same seriousness as the purchase itself, not paperwork to get to later.
Frequently asked questions
What is a co-ownership agreement, and how is it different from choosing joint tenancy or tenants in common?
A co-ownership agreement is a private contract between the people buying a property together, separate from the registered title-holding decision itself. Title-holding, whether you register as joint tenants or tenants in common, decides legal questions like what happens to a share on death and whether shares must be equal; the co-ownership agreement is an additional document the co-owners sign between themselves covering ownership shares, cost-sharing, use of the property, and what happens if someone wants out. Ontario’s own guidance describes it as the document that protects everyone if a dispute comes up later and recommends proper legal advice to prepare one. You need both pieces: a title-holding choice registered on the deed, and a co-ownership agreement covering everything the deed doesn’t.
Do ownership shares have to be split 50/50?
No. Under tenants in common specifically, co-owners can hold any split they agree to, unlike joint tenancy, which requires equal shares. An unequal split, commonly where one buyer contributed more to the down payment or carries more of the ongoing costs, is common and should be recorded precisely in the co-ownership agreement: the actual contributions, the resulting ownership percentage, and how that percentage was calculated. An unequal split also tends to need different decision-making and exit terms than an even 50/50 partnership would, since the larger owner typically needs more say over major decisions and the smaller owner needs a buy-out path that’s realistic given the actual gap between the shares.
What should the agreement say about costs like the mortgage and property tax?
It should name exactly how mortgage payments, property tax, operating expenses, major repairs, insurance, and condo fees if applicable get split between the owners, and set out a practical mechanism for actually moving the money, commonly a shared account each owner contributes to on a schedule with a clear record of what’s been paid. It should also decide in advance what happens if one owner falls behind: a defined cure period, followed by a specific remedy such as the other owner covering the gap and being owed it back, is a common approach. There’s no single required formula for any of this, but deciding it before a payment is ever missed avoids turning the first shortfall into a dispute from scratch.
What happens if one owner wants to sell their share and the others don’t?
A well-drafted agreement gives the co-owners a defined path for this before it ever becomes a problem, typically a right of first refusal so the remaining owners get the chance to buy the departing owner’s share before it goes to an outside buyer, along with an agreed method for pricing it. A further, more complete protection is a shotgun clause, where one owner names a price for their share and the other must either buy at that price or sell their own share at the identical number, which tends to produce a fair price because both sides have to be willing to accept their own number from either side of the deal. Without any agreement covering this, resolving a deadlock generally means relying on the Partition Act’s own court process instead, which is slower and less predictable than settling the mechanism privately in advance.
Is a co-ownership agreement legally required to buy property with someone else?
No. You can close on a property with a co-buyer without one. It’s strongly advisable rather than mandatory, which is exactly why it gets skipped: nothing stops the purchase from happening without it. The risk shows up later, when a disagreement, a relationship ending, a death, or simply one owner wanting out happens with nothing in writing beyond the title registration itself to settle it. For a married couple, the Family Law Act fills in some of that gap automatically. For anyone else buying together, a co-ownership agreement is the only document doing that job, which is why it belongs as part of the purchase itself, not optional paperwork for later.
Buying property with someone who isn’t a spouse works out better when the hard questions get answered on paper before closing, not after something goes wrong. If you’re about to buy with a friend, a sibling, a partner, or a co-investor, browse current Toronto listings while you get the agreement itself drafted alongside the purchase, and see our complete Toronto real estate guide or the rest of our guides for everything else the purchase touches.