Originally published: November 2, 2017 | Last updated: April 16, 2025
TL;DR: There are six valid legal grounds to challenge a Will in Canada: lack of testamentary capacity, lack of valid execution, lack of knowledge and approval, failure to provide for dependants, undue influence, and fraud/forgery. Common complaints like “it’s not fair” or “I was promised something” are not valid grounds. Challenging a Will is expensive ($10,000-$100,000+) and rarely successful without strong evidence.
The process to contest a Will requires expensive legal fees and extended court proceedings which makes it difficult to achieve success. Canadian courts protect testators from changes to their estate distribution choices which they establish through their last will. You need to show particular legal reasons which courts require to change a Will instead of showing your disagreement with the deceased person’s wishes. The process of understanding acceptable legal grounds will help you avoid spending more than fifty thousand dollars in attorney fees. Our previous article presents additional details about the reasons which people need to fight against a Will.
Yes, but successfully contesting a Will is difficult, expensive, and time-consuming. Canadian courts respect a testator’s right to distribute their estate as they choose. To overturn a Will, you must prove specific legal grounds, not simply that you disagree with the deceased’s decisions. Understanding the difference between valid and invalid grounds can save you tens of thousands of dollars in legal fees. For a broader overview, see our earlier article on grounds for contesting a Will.
What Are NOT Valid Grounds to Challenge a Will?
Before examining valid grounds, understand what does not work:
- “I was verbally promised something”: Oral promises are not legally binding in estate planning. Only what is written in the Will counts.
- “The person wrote their own Will using software”: Self-prepared Wills (including those from online services) are legally valid if properly signed and witnessed. The method of preparation is not grounds for challenge.
- “I thought I was entitled to an inheritance”: There is no automatic entitlement to inherit from anyone’s estate (except for dependant claims in some provinces).
- “The Will isn’t fair”: A testator has broad freedom to distribute their estate as they wish, even if others consider it unfair.
The following points demonstrate which grounds for contesting a Will do not exist although valid grounds need to be examined:
The estate planning system does not recognize oral promises which people make to each other. Only what is written in the Will counts.
The testator must have understood: what a Will is, the nature and extent of their assets, who would naturally expect to benefit, and how the Will distributes their property. Challenges often arise when Wills are made late in life during cognitive decline, dementia, or while under heavy medication. This is the most commonly litigated ground. Writing your Will while clearly healthy is the strongest defence.
Self-prepared Wills obtained through online services become legally valid when you sign them correctly and witnesses confirm your signature. The method of preparation is not grounds for challenge.
The Will must meet provincial signing requirements: signed by the testator, witnessed by two adults simultaneously, with witnesses who are not beneficiaries. Missing any requirement can invalidate the entire Will. Using a proper Will service with clear signing instructions prevents this.
People have no right to receive inheritance from any estate except for dependent claims which some provinces recognize.
The testator must have known and approved the contents of their Will. If someone else prepared the Will and the testator signed without understanding what it said, particularly if the person who prepared it benefits from it, the Will can be challenged on this ground.
A person who creates a Will can distribute their estate in any way they want even when others find their choices unjust.
Most provinces allow legal dependants (spouse, minor children, and in some provinces adult children or other dependants) to challenge a Will that fails to adequately provide for them. Even an intentional disinheritance can be overridden by the court if a dependant successfully claims under provincial dependant relief legislation.
What Are the Valid Legal Grounds?
If someone in a position of power or trust coerced the testator into making a Will that does not reflect their genuine wishes, the Will can be invalidated. Signs include isolation of the testator, sudden changes to the Will benefiting the influencer, and involvement of the beneficiary in the Will-writing process.
1. Lack of Testamentary Capacity
A Will created through fraud (deliberate misrepresentation of facts to influence the testator) or forgery (a fake signature or fabricated document) is invalid. Proving fraud requires clear evidence and is among the most difficult grounds to establish.
The testator needed to understand Will definition along with their total asset value and which family members would receive benefits and how their assets would distribute through the Will. People face problems when they create Wills during their final years because their mental abilities deteriorate and they develop dementia and receive strong medication. The most frequently disputed basis exists in this area. You need to write your Will while you maintain complete physical and mental wellness because this action creates the most effective protection.
Contesting a Will in Canada typically costs $10,000 to $100,000 or more in legal fees, depending on the complexity and duration of the dispute. Cases can take years to resolve. Even if you win, legal costs may consume a significant portion of whatever you receive. Courts can also order the losing party to pay the winner’s costs. Before challenging a Will, consult an estate litigation lawyer for an honest assessment of your chances and costs.
2. Lack of Valid Execution
The best defence is a properly prepared Will: use a reputable service like LegalWills.ca, write it while clearly of sound mind, follow all signing requirements, provide for legal dependants, act independently without outside influence, and update regularly.
Tim Hewson is one of the founders of LegalWills.ca.
He has over 20 years of experience helping people to write their Will and other estate planning documents. He has been interviewed by many of the major news media outlets including CTV, Global News, The Toronto Star, and other leading Canadian publications. He has also contributed to a number of financial planning books.
Throughout his career, Tim has written extensively on the subject of Will writing and estate planning.
