A joint tenancy must display ‘the four unities’: unities of possession, interest, title, and time.

“Unity of possession” means that no co-owner is entitled to the possession of any particular part of the property to the exclusion of the other co-owner.

“Unity of interest” means that joint tenants hold the same interest. Tenants in common, however, may hold in different shares or proportions.

“Unity of title” means that the joint tenants must derive their interest from the same document or act. They must acquire their interest under the same instrument, e.g. an assignment of land.

“Unity of time” means that the joint tenants must acquire their interest at the same time.

A joint tenant does not hold any interest in the property in his individual capacity. His only interest is that which he holds jointly with his fellow joint tenant(s). A joint tenant is said to hold the whole with other joint tenant(s) but nothing by himself. There is only one estate in property which is held jointly and, although the joint tenants between themselves may have distinct rights, to everyone else, they are regarded as a sole owner.

If any one of the four unities is missing, then the co-owners are tenants in common, not joint tenants.

When a joint tenant dies, his interest is automatically extinguished and the surviving joint tenant(s) become(s) entitled to the property. If there are two joint tenants, the surviving tenant will become the sole owner of the property. If there are more than two join tenants, the shares of the late joint tenant will be divided and pass to the surviving tenants in equal shares. This special feature of a joint tenancy is known as the “right of survivorship”. The right of survivorship is the right of a person to property by reason of his having survived another person who had an interest in it.