How to Contest a Will in Ontario: Grounds, Costs and Deadlines

Estate litigation lawyer reviewing documents during a will challenge in Ontario

Losing a loved one is hard enough without facing questions about the validity of their will. If you suspect a will does not reflect the true intentions of the deceased, or you believe you have been unfairly excluded, you may have grounds to contest it.

This guide explains who can bring a challenge, what you have to prove, what it realistically costs, and what evidence actually decides these cases in Ontario courts.

What are the legal grounds to contest a will in Ontario?

There are four main grounds: lack of testamentary capacity, undue influence, suspicious circumstances, and improper execution. Fraud and forgery form a fifth, rarer category. A will challenge must fit one of these. Disagreeing with how an estate was divided is not, on its own, a legal ground.

This is the first thing to understand, and it is where most challenges fail before they begin. Ontario recognises testamentary freedom. A mentally capable person has the legal right to distribute their property as they wish, including in ways their family finds unfair, unkind, or inexplicable. A court will not rewrite a will simply because the outcome seems wrong.

To succeed, you must prove on a balance of probabilities that one of the following applies.

Lack of testamentary capacity

The most common ground. The deceased must have had a “disposing mind and memory” when the will was signed — broadly, they must have understood what a will does, the general extent of their property, and who had a moral claim on their estate, free of any delusion distorting that judgment. This test comes from Banks v. Goodfellow, and it remains the standard Ontario courts apply.

Capacity challenges turn almost entirely on medical evidence and timing. We cover the test, the evidence, and how dementia diagnoses are treated in detail here: proving lack of testamentary capacity in Ontario.

Undue influence

Undue influence means coercion, not persuasion. Nagging, flattery, and ordinary family pressure do not meet the threshold. You must show the will reflects the wishes of the influencer rather than the deceased — that their mind was dominated and overborne to the point where the document was no longer their own decision.

It is a demanding standard, and it is rarely proven by direct evidence. It is usually established through a pattern: isolation from other family members, sudden control over finances and appointments, and a dramatic change in the estate plan that benefits the person doing the controlling.

Suspicious circumstances

This ground is less well known and often the most useful. Normally a will that appears properly signed is presumed valid, and the person challenging it carries the burden. If you can establish suspicious circumstances, that presumption falls away and the person putting the will forward must prove it is valid.

Circumstances that courts have treated as suspicious include:

A sudden, dramatic departure from an estate plan that stood for decades
Physical or social isolation of the deceased from long-standing family, friends, or advisors
The main beneficiary arranging the lawyer’s appointment, driving the deceased there, or completing an online will kit on their behalf
A will prepared and signed while the deceased was seriously ill or hospitalised
A beneficiary present in the room while instructions were given

Improper execution

Under Ontario’s Succession Law Reform Act, a formal will must be in writing and signed at its end by the testator in the presence of two witnesses, who must both be present at the same time and sign in the testator’s presence.

A beneficiary can act as a witness, but doing so generally voids the gift to them. Ontario courts now have limited power to validate documents that fail to meet these formalities where the document still represents the deceased’s testamentary intentions, but that power has limits — a wholesale failure of the basic requirements can still invalidate a will.

Fraud or forgery

Less common, and more serious. This covers a signature that is not the deceased’s, pages substituted after signing, or a will procured by deliberate deception about material facts.

Who can contest a will in Ontario?

You need legal standing, which generally means you stand to gain if the will is set aside. Being upset about the outcome is not enough — you must be someone whose position would improve under a prior will or under Ontario’s intestacy rules.

The following usually have standing:

Spouses, married or common-law. Note that married and common-law spouses have materially different rights on intestacy in Ontario.
Children, including adult children and legally adopted children
Dependants — anyone the deceased was supporting or had a legal obligation to support, which can include a parent, sibling, or former spouse
Beneficiaries named in an earlier will, even if they are left out of the current one
Anyone who would inherit on intestacy if no valid will existed
Creditors and estate trustees, in narrower circumstances

Standing is worth confirming early. It determines whether you can bring a challenge at all, and it shapes what you would actually recover if you won.

How long do you have to contest a will in Ontario?

Act quickly. Limitation periods in estate matters are short, contested in their application, and unforgiving once missed. The basic limitation period under the Limitations Act, 2002 is two years, but Ontario courts have differed on when that clock starts for a will challenge — some decisions run it from the date of death, others apply discoverability.

Dependant support claims are subject to a separate and much shorter deadline, generally six months from the grant of the certificate of appointment, with limited exceptions.

Because the law here is unsettled and the consequences of being late are absolute, this is not a deadline to calculate yourself. We set out the competing authorities and what they mean in practice here: how long you have to challenge a will in Ontario.

How much does it cost to contest a will in Ontario?

Cost depends almost entirely on how far the matter goes. A challenge resolved at mediation costs a fraction of one that runs through discovery to trial, and most estate disputes settle well before a courtroom.

The bigger financial question is not your own legal fees but the risk of paying someone else’s.

Rather than a single figure, it helps to understand what actually drives the cost of a will challenge. Two cases with identical legal grounds can differ by a factor of ten depending on these factors.

Cost driver	Lower cost	Higher cost
How far it goes	Resolved at or before mediation	Full discovery and a contested trial
Expert evidence	No capacity expert required	Retrospective capacity assessment by a medical expert
Document volume	A recent will, one drafting lawyer, clear records	Years of medical, banking and care records across multiple providers
Number of parties	Two siblings disputing one will	Multiple beneficiaries, a blended family, separately represented
Cooperation	The estate trustee produces documents voluntarily	Motions required to compel production at each stage
Estate complexity	A house and bank accounts	A business, trusts, foreign assets, or property to be valued

Most estate disputes in Ontario resolve before trial, which is why the first question a lawyer should answer is not what a full trial would cost, but whether your matter is likely to need one.

Powell Litigation will give you a cost estimate specific to your circumstances at the initial consultation, once we know which of the factors above apply to your situation.

Will the estate pay my legal fees?

Not automatically, and assuming otherwise is a costly mistake. Ontario courts once routinely ordered estate litigation costs paid out of the estate. That approach changed with the Court of Appeal’s decision in McDougald Estate v. Gooderham, which directed courts to start from ordinary civil costs principles — meaning the unsuccessful party generally pays a portion of the successful party’s costs.

Costs may still be ordered out of the estate in defined situations, most commonly where the testator’s own conduct or an ambiguity in the will caused the litigation, or where there were reasonable grounds to investigate the circumstances of the will. But that is an exception argued for, not a default.

The practical consequence: a challenge brought on weak grounds can leave you paying your own fees and a share of the other side’s. An honest early assessment of the merits is the single most valuable thing a lawyer does in these cases.

How do you actually start a will challenge?

In most cases the first step is filing a Notice of Objection with the court, which stops a certificate of appointment of estate trustee from being issued without notice to you. This is a protective step, and it is often urgent — once probate is granted and assets are distributed, recovering them becomes substantially harder.

From there, the process typically runs:

Notice of Objection filed, preserving your position
Application or claim commenced, setting out the grounds relied on
Document production — the drafting lawyer’s file, medical records, financial records
Examinations of the parties and relevant witnesses
Mediation, which is mandatory for estate matters in Toronto
Hearing or trial, if the matter does not resolve

Most challenges resolve at or before mediation. You can read more about that route here: resolving estate disputes through mediation.

What evidence actually wins a will challenge?

Judges decide these cases on documents and timelines, not on family history. The most common reason a challenge fails is that it is built on grievance rather than proof — a lengthy account of twenty years of family conflict tells a judge nothing about the deceased’s mental state on the day the will was signed.

The evidence that decides these cases is narrower and far more specific:

Medical records and cognitive assessments establishing what the deceased’s mental state actually was on or near the date of execution — not months before or after
Pharmacy records showing medications that may have affected cognition
The drafting lawyer’s complete file, including contemporaneous notes. Did they assess capacity? Did they meet the deceased alone? Or did they take instructions with the principal beneficiary sitting in the room?
Financial records reconstructing when control over the deceased’s money and affairs shifted, and to whom
Evidence of isolation — changed locks, intercepted calls, cancelled visits, a new phone number
The prior will and the instructions behind it, showing what the deceased intended before the change

Built properly, these sources produce a chronology. A chronology is what persuades a court — it shows exactly when circumstances changed, who was present when they did, and what the deceased was capable of understanding at the moment that mattered.

What happens if the will is found invalid?

The estate reverts to the most recent valid will. If there is none, Ontario’s intestacy rules apply. This is why identifying whether an earlier will exists is one of the first questions in any challenge — setting aside a will does not mean the estate is divided as you think it should be.

Under the intestacy provisions of the Succession Law Reform Act, a surviving married spouse is entitled to a preferential share of the estate before the remainder is divided with any children. Common-law spouses do not have the same entitlement on intestacy, which is a frequent and expensive surprise for families.

A court may also find only part of a will invalid, leaving the remainder standing.

Blended families and second marriages

Estate disputes concentrate in blended families, and the reason is structural rather than personal. Children from a first relationship, a second spouse, and a common-law partner can all have competing claims that a single will was never designed to reconcile.

Common flashpoints include a second spouse inheriting the matrimonial home while children from a first marriage receive nothing, mutual wills made during a first marriage that a survivor later changes, and adult children who provided years of care receiving less than a recently arrived partner.

If this describes your situation, standing and the possibility of a dependant support claim are both worth assessing early — the six-month deadline on support claims makes delay particularly costly.

Speak with a Toronto estate litigation lawyer

If you believe a will does not reflect what your loved one actually wanted, time is working against you. Estate assets can be distributed and spent while a challenge is being considered, and the deadlines in this area are short.

Powell Litigation is a litigation-only firm. Our Toronto estate litigation lawyers act for beneficiaries, dependants, and estate trustees in contested estates throughout Ontario, and we will tell you honestly whether a challenge is worth bringing before you spend money finding out.

Schedule a case evaluation with Powell Litigation or call (437) 222-2234.

Providing peace of mind every step of the way

How to Contest a Will in Ontario: A Legal Guide