What are mutual wills?
Mutual wills are wills made by two people under a binding agreement not to change them after the first person dies. Unlike mirror wills, the survivor cannot revoke the arrangement — equity imposes a constructive trust over the estate to enforce the agreed terms.
Mutual wills are rare and courts are reluctant to find them unless there is clear evidence of a genuine contract not to revoke, separate from the wills themselves. Similar wording alone is not enough.
They are also inflexible by design. The survivor may live for decades, during which circumstances, tax rules and family relationships all change, and none of it can be responded to. Assets acquired after the first death may also be caught.
In practice a life interest trust delivers the same protection with far more control and far less litigation risk, which is why mutual wills are seldom recommended today.