Land: severance of joint tenancy
If a joint tenant wishes to dispose of the whole or part of his or her interest in the land, without the other tenant or tenants doing likewise, the joint tenancy must be severed and converted into a tenancy in common, at which point the joint tenancy will come to an end. Only then can the tenant in question dispose of an interest in the land.
If, after the disposal, there remain two or more persons with concurrent interests in the land, they will be tenants in common rather than joint tenants. This must follow, since they will have acquired their interests at different times.
There are other methods of converting a joint tenancy to a tenancy in common, for example when the joint tenants agree that this should occur. Such a conversion will only have Capital Gains Tax consequences if one or more of the former joint tenants have reduced their interests in the land.