Key Takeaways:
- A Will may be invalid in Western Australia if it wasn’t properly signed or witnessed, if the Will-maker lacked testamentary capacity, or if there are concerns about undue influence, fraud, or suspicious circumstances.
- Under the Wills Act 1970 (WA), a valid Will generally must be in writing, signed by the testator, and witnessed correctly by two people.
- An invalid Will isn’t the same thing as an unfair Will. Even if a person feels disappointed by the contents of a Will, the document may still be legally valid.
- If a Will is found invalid, the Supreme Court of Western Australia may rely on an earlier valid Will or apply intestacy rules under the Administration Act 1903 (WA).
A Will is one of the most important legal documents a person can make. But not every Will is legally valid simply because it exists.
Our 2026/2027 Inheritance State of Play in WA Report found that 42% of Western Australians either do not have a Will or are unsure if they do. When outdated Wills are included, almost 3 in 5 are at high risk of unintended outcomes for their estate, and potential disputes.
When concerns arise about the validity of a Will, the consequences can be significant. Families can find themselves in complex disputes over whether the document truly reflects the intentions of the deceased person, whether proper legal requirements were followed, and ultimately, who should inherit from the estate.
In this guide, we explain when a Will might be found invalid in Western Australia, what the Supreme Court considers in validity disputes, and what may happen if a Will is set aside.
When is a Will invalid in Western Australia?
In Western Australia, a Will may be found invalid where the law cannot safely recognise it as the deceased person’s final and genuine expression of intention.
Some invalidity issues are procedural. For example, the Will may not have been properly signed or witnessed according to the formal requirements set out in the Wills Act 1970 (WA). Even relatively small mistakes in the execution process can create significant problems later, particularly when there are disputes between family members or questions around the authenticity of the document.
Other challenges relate to the state of mind and intention of the Will-maker at the time the Will was made. The Supreme Court of Western Australia may need to consider whether the person had testamentary capacity, whether they understood and approved the contents of the Will, and whether they were acting freely and voluntarily.
There can also be broader integrity concerns surrounding a Will. Allegations of undue influence, fraud, forgery, suspicious circumstances, revocation, or the existence of a later Will can all raise questions about whether the document should be legally recognised.
Importantly, whether a Will is valid ultimately depends on the evidence and the particular circumstances of the estate.
Legal requirements for a valid Will in Western Australia
Before the Supreme Court of Western Australia can recognise a Will as legally valid, certain legal requirements must be satisfied. Some of these requirements relate to how the Will was prepared and signed. Others relate to the mental capacity and intentions of the Will-maker at the time the document was created.
Where those requirements aren’t met, the validity of the Will can be challenged.
Formal requirements under the Wills Act 1970 (WA)
In Western Australia, the formal requirements for a valid Will are primarily set out in the Wills Act 1970 (WA).
Generally, for a Will to be legally recognised, it must:
- be in writing, whether typed or handwritten
- be signed by the Will-maker (also called the testator)
- be signed in the presence of at least two witnesses
- be signed by those witnesses in the presence of the Will-maker and each other
These formal requirements exist to help protect against fraud, mistake, or disputes later on about whether the document truly reflects the intentions of the deceased person.
Dating a Will is also important, particularly where multiple versions may exist. However, an undated Will isn’t automatically invalid. Instead, it can create additional complications when applying for a Grant of Probate or proving which document was intended to operate as the final Will.
Read more: Do you need a lawyer to make a Will in Australia?
Testamentary capacity, knowledge and free intention
A valid Will also depends on the Will-maker having testamentary capacity at the time the Will is made.
Broadly speaking, the person must understand:
- that they are making a Will
- the general nature and extent of their assets
- who might reasonably expect to benefit from their estate
The Will-maker must also know and approve of the contents of the document and make the Will freely, without coercion or improper pressure from another person. They must also be unaffected by any mental disorder or condition that affects their judgment or ability to make rational decisions about their estate.
This is an important distinction. A Will isn’t considered valid simply because it was signed correctly. The Court must also be satisfied that the document genuinely reflects the Will-maker’s own intentions, and that he or she had sufficient capacity to make the Will.
Can the Supreme Court accept an informal Will?
In some circumstances, the Supreme Court of Western Australia can accept an informal document as a valid Will, even where strict legal requirements have not been followed.
This might include documents such as unsigned drafts, notes, electronic records, or other materials that clearly record the deceased person’s testamentary intentions.
However, these cases are often complex and highly fact-specific. The Court must be satisfied that the deceased intended the document to operate as their Will, and disputes about informal Wills frequently involve detailed evidence and contested probate proceedings. This can be extremely time-consuming and costly for all involved.
For that reason, relying on an informal Will or a DIY estate planning approach can create significant uncertainty for the people left behind, and result in unintended costs to the estate.
Common reasons a Will may be found invalid
Questions about the validity of a Will often arise when something about the circumstances doesn’t feel quite right.
Importantly, not every unusual or unfair situation will invalidate a Will. The Supreme Court of Western Australia looks closely at the evidence surrounding the making of the Will, including medical evidence, witness accounts, solicitor file notes, and the broader circumstances of the estate.
Below are some of the most common reasons a Will may be challenged or found invalid in WA.
1. Lack of testamentary capacity
One of the most common grounds for challenging a Will is an allegation that the Will-maker lacked testamentary capacity at the time the document was signed.
This issue often arises in situations where the Will-maker suffers from:
- dementia
- Alzheimer’s disease
- cognitive decline
- confusion or memory loss
- serious illness near death
- medication affecting mental clarity
To have testamentary capacity, a person must understand that they’re making a Will, broadly understand the assets they own, and understand who may reasonably expect to benefit from their estate.
Importantly, capacity is assessed at the time the Will was made, not across the person’s life generally. A person may have periods of confusion or decline but still experience a “lucid interval” during which they are capable of making a valid Will. The key is whether they had requisite capacity at the particular time they made their Will.
Disputes about capacity are often heavily evidence-based. Medical records, treating doctors, witness observations, and solicitor notes can all become important in determining whether the Will-maker understood what they were doing when the Will was signed.
For more on this issue, read our article on mental capacity and Will validity and the legal standards the Court applies in these disputes.
2. Undue influence or coercion
A valid Will must reflect the Will-maker’s own free intentions.
If another person pressures, manipulates, intimidates, or coerces someone into making or changing a Will, the Court may find that the document doesn’t genuinely reflect the wishes of the deceased person.
These cases commonly arise where there are:
- relationships of dependency
- family conflict
- social isolation
- controlling behaviour
- carers or relatives heavily involved in the person’s day-to-day life
For example, concerns can arise where one family member controls access to an elderly parent, arranges the Will appointment, or becomes heavily involved in discussions about inheritance.
However, persuasion alone isn’t necessarily undue influence. Family members often express opinions or encourage certain decisions. They may also legitimately be the Will-maker’s trusted support person and genuinely have their interests at heart. The legal question is whether there is objectively actual pressure and whether this pressure becomes so significant that the Will-maker’s free judgment is effectively overborne.
Undue influence claims can be difficult to prove because the alleged conduct often occurs behind closed doors. Suspicion alone is usually not enough. In many cases, proving undue influence requires detailed evidence about the relationship dynamics, the circumstances surrounding the Will, and the extent of the pressure allegedly applied.
3. Fraud or forgery
A Will may also be invalid where fraud or forgery is involved.
Examples can include:
- fake signatures
- fabricated Wills
- altered pages
- changes made after signing
- misleading a person about the nature of the document they are signing
In some cases, for example, a vulnerable or elderly person may be deceived into signing a document without fully understanding it is a Will or what its contents mean.
Forgery allegations are serious and often require strong, detailed evidence. The Court may consider handwriting analysis, witness testimony, drafting records, and forensic evidence when determining whether the document is genuine.
4. Improper execution
Problems with the execution process are another common source of invalidity disputes.
Even where a document clearly reflects someone’s wishes, it may still be challenged if it wasn’t signed and witnessed correctly under the Wills Act 1970 (WA).
Common issues include:
- missing witness signatures
- witnesses not being present together
- the Will-maker not properly signing the document
- informal amendments made after signing
- DIY Wills that fail to meet one or more legal requirements
These situations often arise where people attempt to prepare or change a Will themselves without legal guidance. For a deeper look at the risks involved, read our article on the dangers of DIY Will kits in Australia and the common mistakes that can lead to costly estate disputes later on.
Although the Supreme Court can sometimes accept an informal Will, relying on that process is risky and can expose the estate to costly disputes about whether the document should be recognised.
5. Lack of knowledge and approval
For a Will to be valid, the Will-maker must know and approve of its contents – in other words, they must understand what the Will is doing, and be satisfied that it correctly reflects their intentions.
Knowledge and approval issues can arise where there are concerns that the Will-maker signed the document without properly understanding what it said or without appreciating its legal effect.
The risk can be higher where the Will-maker:
- had poor eyesight or hearing
- faced language barriers
- was heavily reliant on another person
- was vulnerable due to illness or age
- signed documents prepared by someone who stood to benefit significantly
For example, concerns may arise where a beneficiary plays a major role in arranging or preparing the Will, and the circumstances suggest the Will-maker may not have independently understood or approved the contents.
In these situations, the Court may need to look closely into the circumstances to determine whether the document truly reflected the Will-maker’s informed intentions.
6. Suspicious circumstances
Sometimes a Will may appear unusual or inconsistent in a way that raises broader concerns about its validity.
Examples of suspicious circumstances can include:
- major changes made shortly before death
- the sudden exclusion of close family members
- a significant benefit given to a carer or other influential person
- secrecy surrounding the preparation of the Will
- isolation of the Will-maker from family or advisers
- unusual or irrational instructions
Suspicious circumstances don’t automatically invalidate a Will. However, they may require stronger evidence to satisfy the Court that the document genuinely reflected the testator’s intentions and was made freely and knowingly.
7. Revocation, marriage, divorce and later Wills
Disputes can also arise where there are questions about whether a Will was revoked or replaced.
Generally, a later valid Will revokes an earlier Will. Problems can occur where multiple versions of a Will exist or where uncertainty arises about which document was intended to operate as the final Will.
Marriage and divorce can also affect the operation of a Will in Western Australia, particularly where the document wasn’t updated following major life changes. Generally a Will is revoked by later marriage or divorce unless the Will specifically contemplated it at the time of signing.
Physical damage or tampering can create additional complications. Removing pages, marking the document, unstapling it, or destroying part of the Will may raise questions about whether the Will-maker intended to revoke it.
These disputes are often highly fact-specific and can end up significantly affecting who ultimately inherits from the estate.
Invalid Will vs unfair Will: Understanding the difference
It should be clearly understood that an invalid Will isn’t the same thing as an unfair Will.
An invalid Will is a Will the law doesn’t legally recognise. This may involve issues such as lack of testamentary capacity, undue influence, fraud, or failures in the way the Will was signed and witnessed.
An unfair Will, however, may still be legally valid.
For example, a person may choose to leave unequal gifts to their children, exclude a family member, or leave most of their estate to a new partner. While those decisions can cause significant distress to disappointed beneficiaries, they don’t automatically invalidate the Will if it was otherwise made within the legal requirements of the Wills Act.
In many cases, the real question here isn’t whether the Will is invalid, but whether an eligible person has grounds to bring a Family Provision Claim or contest a Will in WA. If you’d like to better understand the legal process involved, read our guide on contesting or challenging a Will and what the process can look like in Western Australia.
What happens if a Will is found invalid?
If the Supreme Court of Western Australia determines that a Will is invalid, the document may be set aside either in full or in part.
What happens next depends on the circumstances of the estate and whether an earlier valid Will exists.
In many cases, a previous valid Will may apply instead. This can significantly change who inherits from the estate, particularly where the invalid Will contained major changes to beneficiaries or distributions.
If there is no earlier valid Will, then the estate may instead be distributed according to the intestacy rules set out in the Administration Act 1903 (WA). These rules determine who inherits when a person dies without a legally valid Will.
Questions about validity can also affect the probate process. A Grant of Probate may be delayed, disputed, or refused altogether while the Court determines which document, if any, should be recognised as the deceased person’s final Will.
Who benefits if a Will is set aside?
Where a Will is declared invalid, the people who ultimately benefit from the estate may be very different from those named in the disputed document.
In some situations, beneficiaries under an earlier valid Will may inherit instead. In others, eligible relatives may inherit under intestacy laws, including spouses, children, or other family members recognised under the Administration Act 1903 (WA). What each of these persons stands to inherit is fixed according to a formula and based on the size (value) of the estate.
This can produce outcomes that families don’t expect, particularly where there are blended families, estranged relationships, or competing versions of a Will.
Practical examples of invalid Wills in WA
Questions about the validity of a Will often arise in emotionally difficult and highly personal circumstances. While every estate dispute depends on its own facts, the examples below illustrate some common situations where concerns about validity may emerge.
Example #1: An elderly parent changes their Will shortly before death
An elderly parent is diagnosed with advanced dementia and admitted to hospital. A new Will is signed only weeks before their death, dramatically changing the distribution of the estate and excluding one of their children.
In this type of situation, questions may arise about whether the Will-maker had testamentary capacity at the time the document was signed, particularly if there is medical evidence of cognitive decline, confusion, or impaired decision-making.
Example #2: A carer becomes the main beneficiary
A vulnerable person becomes increasingly dependent on a neighbour or carer in the final years of their life. Shortly before their death, a new Will leaves most of the estate to that person instead of close family members.
This may raise concerns about undue influence, suspicious circumstances, and whether the Will-maker genuinely understood and approved the contents of the document. The Court may closely examine the circumstances surrounding the preparation and signing of the Will.
Example #3: A DIY Will is not properly witnessed
A person prepares their own Will using an online template or DIY Will kit. After their death, the family discovers the document was signed without the required witnesses being present together.
Even where the document appears to reflect the deceased person’s wishes, improper execution can create significant legal uncertainty and disputes about whether the Will should be recognised by the Court.
Example #4: A family member controls access to the Will-maker
An ageing parent becomes socially isolated and one adult child begins controlling access to them, including communication with other family members and attendance at legal appointments.
If a new Will is later made in circumstances where that child receives a substantial benefit, questions may arise about coercion, dependency, or whether the Will-maker was acting freely and independently.
These situations don’t automatically mean a Will is invalid. However, they are examples of circumstances where closer legal scrutiny and evidence may be required.
How to avoid an invalid Will
While no Will is completely immune from challenge, there are practical steps that can significantly reduce the risk of disputes about validity later on.
These include:
- having your Will prepared or reviewed by an experienced Wills and estates lawyer
- ensuring the Will is properly signed and witnessed in accordance with WA law
- avoiding DIY Wills or informal amendments
- updating your Will after major life changes such as marriage, divorce, separation, or the birth of children
- destroying outdated versions once a new Will has been signed
- keeping clear records where capacity or family conflict may later become an issue
- storing the original Will in a safe but accessible location
- communicating your intentions clearly where appropriate to reduce future misunderstandings and disputes
- considering more sophisticated estate planning structures, such as Testamentary Trusts, where appropriate
Many validity disputes arise not because someone intended to create problems, but because important legal or practical safeguards were overlooked.
A carefully prepared Will not only improves the likelihood that your wishes will be upheld, but can also provide greater certainty and stability for the people you leave behind.
When should you seek legal advice about a Will’s validity?
It may be worth seeking legal advice if there are concerns about:
- testamentary capacity or cognitive decline
- pressure, coercion, or undue influence
- suspicious last-minute changes to a Will
- fraud, forgery, or missing documents
- whether proper legal requirements were followed
Validity disputes are often highly evidence-based. Medical records, witness accounts, previous Wills, and solicitor file notes can all become important in determining whether a Will should be upheld by the Supreme Court of Western Australia.
Protect your Will and your legacy
Questions about whether a Will is invalid can be legally and emotionally complex.
If something about a Will doesn’t feel right, it’s worth understanding where you stand early. Solomon Hollett Lawyers advises clients across Western Australia on contested estates and contesting a Will matters, including disputes involving the validity of a Will. If you need guidance from an experienced Will contest lawyer, we offer a free 15-minute phone call where you can briefly discuss your situation and gain clearer guidance on whether you may have grounds to challenge a Will or explore other legal options available to you.
Dealing with an inheritance dispute, estate administration or probate matter?
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