Joint tenancy and tenancy in common are the two most common forms of concurrent property ownership in Canada.
In a joint tenancy, the “four unities” of title, interest, time and possession are present and co-owners hold an equal interest in the property as a unified whole. The common law treats joint tenants as a single tenant: each holding the whole for all, with no distinct shares held by anyone.
In contrast, in a tenancy in common one co-owner may hold a greater proportionate interest in the property than the other co-owner(s): Hansen Estate v. Hansen, 2012 ONCA 112 at paras. 29-30; Felske Estate v. Donszelmann, 2007 ABQB 682 at para. 31, aff’d 2009 ABCA 209; Rathwell v. Rathwell,  2 S.C.R. 436 at 459.
Unity of title means the title of each joint tenant arose from the same act or instrument. Unity of interest means their holdings are perfectly equal in nature, extent and duration. Unity of time means all the interests vested simultaneously. Unity of possession means each joint tenant has a right to present possession and enjoyment of the whole property, but no right to exclusive possession of any individual part of the whole. Assuming all four unities are present, the question of whether a joint tenancy or a tenancy in common has been created is determined by the intention of the grantor: B. Ziff, Principles of Property Law, 6th ed. (Toronto: Carswell, 2014) at 336; Felske Estate at para. 31.
Joint tenancy is often the chosen form of concurrent ownership for family holdings, usually for estate planning purposes. This is unsurprising. The legal fiction of a unified singularity composed of more than one person may fit comfortably in a family context. Unfortunately, however, unity can be fragile and families are not always happy. As Abella J. remarked in Pecore, when divisions arise that unhappiness often finds its painful way into a courtroom.
The principal and distinguishing characteristic of joint tenancy is the right of survivorship, the jus accrescendi. When one joint tenant dies, his or her interest in the property is extinguished and passes to the surviving joint tenant(s). The right of survivorship is, however, a revocable expectancy that manifests only upon success in the so-called “ultimate gamble” – survival – and then only if the joint estate has not been previously destroyed by an act of severance: Estate of Propst, 788 P.2d 628 at 631 (Cal. Sup. Ct. 1990). When given inter vivos, a gift of survivorship rights is to what is left, if anything, when the gamble is won: Simcoff v. Simcoff, 2009 MBCA 80 at para. 64.
The interest of a tenant in common is different with respect to survivorship. Unlike that of a joint tenant, a tenant in common’s interest in property remains intact upon death and passes into his or her estate: Fuller v. Harper, 2010 BCCA 421 at para. 53.
Importantly, parties may hold legal title to property in one form of co ownership while holding equitable title in another. For example, a mother and daughter may be joint tenants in law and tenants in common in equity with respect to jointly-held property by virtue of a trust or an act of severance. If the mother dies first, the daughter assumes full legal title by right of survivorship, but the mother’s equitable interest, being held in common, passes to her estate and the daughter holds legal title as trustee for the beneficial owners, namely herself and her mother’s estate: Pecore at paras. 4-5; Ziff at 341-342.
Equity leans against joint tenancies: As explained in J. McGhee, ed., Snell’s Equity, 31st ed. (London: Sweet & Maxwell, 2005) at 103, the relevant maxim is that equity is equality.
When a joint tenant dies the whole belongs to the survivor(s) and the deceased’s estate takes nothing, which favours the tenant(s) of longevity and is thus unequal, except perhaps for an equal chance at survival. For this reason, equity often treats persons who are joint tenants at law, such as business partners or unequally contributing co-owners, as tenants in common: Mischel Holdings Pty Ltd. v. Mischel,  VSCA 375 at paras. 60-61.