For many, marriage represents the intermingling of lives, families, and assets. It can also mean coordinating estate plans. Two common forms of coordinated estate plans are mirror wills and mutual wills – both are particularly useful if the couple have children, either together or from prior relationships. Knowing the difference between these two types of estate plans can help you decide which is right for you and your spouse.
“Mirror wills,” sometimes call “reciprocal wills,” are two wills that contain reciprocal terms that are the mirror image of each other. For example, if Will A says: “I leave everything to my husband, and if he dies before me, to my children” then Will B would say: “I leave everything to my wife, and if she dies before me, to my children.” The intended effect of the mirror wills in this example is to ensure that, no matter which spouse dies first, the combined property of the couple will eventually go to their children.
Mirror wills are not without risk. While both spouses are alive, each spouse may feel relatively confident that they are united in their estate plans. However, once the first spouse dies, the surviving spouse may choose to execute a new will which disinherits one or more of their children. In fact, there is no need to wait until the death of the first spouse: relying on the principles of privacy and testamentary freedom, either one of the spouses could revoke their mirror will at any time and execute a new will without telling their spouse. As a result, the children who anticipated inheriting their parents’ assets in the example above may be in for a surprise when the last of their parents die.
In order to ensure that each spouse is bound by their initial agreement regarding their testamentary plans, they will need to sign “mutual wills.”
Mutual wills are the same as mirror wills except that, in addition to signing their wills, the spouses enter into a contract confirming that they will not revoke or change their will (save for correcting errors in the document) without the consent of the other spouse. When one spouse dies, it becomes impossible for the surviving spouse to receive such consent, meaning that the terms of the surviving spouse’s will cannot be altered.
While testamentary freedom is a right afforded to Canadians, it is not an absolute right. The choice of who will benefit from your estate on death is curbed by provincial law (for example, Ontario has enacted legislation to ensure that all dependents are provided support from an estate) and can also be restricted by contract. Canadian courts have found that agreements entered into by spouses which gives up their right to change their mirror wills (now called mutual wills) are enforceable.
Both mirror wills and mutual wills are useful estate planning tools: they can add certainty and predictability to the transfer of assets. However, be aware that if the wrong option is chosen in the circumstances, or the wills and mutual agreements are not drafted properly, litigation may be the unhappy result.
 Rammage v Estate of Roussel, 2016 ONSC 1857 (CanLII) at para. 18 (“Rammage”).