August 12, 2025

By Mark Mikulasik

Creating a will is one of the most important steps you can take to ensure your wishes are respected after your death. But not all wills are legally valid—certain mistakes or circumstances can render a will invalid in Ontario. Here are five common pitfalls to avoid.

1. The Will Wasn’t Properly Signed and Witnessed

Ontario’s Succession Law Reform Act sets out strict rules for how a will must be executed:

• • It must be in writing.
  • It must be signed by the testator (the person making the will).
  • It must be witnessed by two people who are both present at the same time.
  • The witnesses must also sign the will in the presence of the testator and each other.

If these formalities aren’t followed, the will could be found invalid—even if it clearly reflects your intentions.

Holograph wills written entirely in the testator’s handwriting and signed may still be valid without witnesses, but the Succession Law Reform Act and court decisions limit the effectiveness of choosing to do a holograph will.

2. One of the Witnesses Is a Beneficiary

This is a common mistake. If someone who stands to benefit from the will also acts as a witness, they may lose their inheritance. The will itself may still be valid, but that beneficiary’s gift could be void under section 12 of the Succession Law Reform Act.

Tip: Choose two witnesses who are not beneficiaries and have no interest in your estate.

3. The Testator Lacked Mental Capacity

For a will to be valid, the testator must have what’s called “testamentary capacity.” This means they must understand:

• • That they are making a will.
  • The nature and extent of their property.
  • Who might reasonably expect to benefit from the estate (e.g., spouse, children).

If someone lacked capacity due to illness, cognitive decline, or undue influence at the time the will was signed, the will can be challenged and potentially set aside.

4. The Will Was Revoked (Intentionally or Not)

A valid will can be revoked in several ways:

• • By physically destroying it (tearing, burning, etc.).
  • By making a new will that expressly revokes previous ones.

Marriage used to revoke a prior will, but no longer since 2022.

If your life circumstances have changed—especially if you’ve married, divorced, or had children—it’s important to revisit your will. Outdated wills can cause confusion and litigation.

5. The Will Was the Product of Undue Influence or Fraud

If a testator was pressured, manipulated, or misled into making a will or changing their beneficiaries, the will can be challenged in court. This is especially relevant in situations involving:

• • Elderly or vulnerable individuals.
  • Caregivers or new companions who suddenly appear late in life.
  • Significant or unusual changes to long-standing estate plans.

Ontario courts take claims of undue influence seriously, and a successful challenge can result in the will being declared invalid.

Takeaways

• A valid will ensures your wishes are respected and your loved ones are protected.
• But even small missteps can lead to legal battles or invalidate your intentions.
• If you’re unsure whether your will—or a loved one’s—meets Ontario’s legal requirements, it’s best to speak with an estate lawyer.
• Better still, just have a lawyer draft it in the first place. The cost is modest.

 

How Weilers LLP Can Help You

Need help reviewing or drafting a will in Ontario? Our estate planning lawyers are here to help. Give us a call and see if we are the right lawyers for you.