Four unities

The four unities

Unity of time 

Interest must be acquired by both tenants at the same time.

Unity of title 

The interests held by the co-owners must arise out of the same instrument.

Unity of interest 

Both tenants must have the same interest in the property.

Unity of possession 

Both tenants must have the right to possess the whole property.

If any of the four unities is broken and it is not a joint tenancy, the ownership reverts to a tenancy in common.

The unique aspect of a joint tenancy is that as the joint tenancy owners die, their shares accrue to the surviving owner(s) so that, eventually, the entire share is held by one person.

A fifth unity

Unity of marriage 

In order for there to be a tenancy by the entirety this fifth unity must be present. Marriage combined with the preceding four unities creates a tenancy by the entirety. A tenancy by the entirety gives rise to certain legal rights, such as rights of survivors, when one spouse is deceased that interest automatically passes to the surviving spouse.

A sixth unity

Unity of unison 

In order for the parties to be united, they must be in unison. This has been criticised by the Law Commission in their 283rd report, entitled 'Unity in Leaseholds'.