What is testamentary capacity?

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Testamentary capacity refers to a person’s mental capability to make a valid will, understanding the nature of what they are doing, the extent of their property, and recognising the claims of potential beneficiaries.

It ensures the testator’s wishes are genuinely theirs, unaffected by mental incapacity.

What constitutes a valid will under testamentary capacity?

A will acts as a method of dictating how property and assets are distributed after someone’s death. Therefore, the validity of a will, to a considerable extent, hinges upon the testator’s testamentary capacity at the time the will is formulated and executed.

The United Kingdom enforces specific prerequisites to ascertain this capacity when someone writes a will, safeguarding the true intentions of the testator from being changed by external influences or incapacitated judgement.

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Scott Taylor

Partner | Private wealth disputes

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Core elements of testamentary capacity

Cognitive comprehension

The testator must distinctly understand the act of making a will and its subsequent implications. This encapsulates an understanding of the assets being bequeathed and the identity of the beneficiaries.


The testamentary act must be voluntary, devoid of undue influence, duress, or coercion, ensuring that the provisions within the will authentically reflect the testator’s wishes.


The testator should possess the mental ability to recall and recognise their properties and beneficiaries. This doesn’t necessitate perfect memory but suffices with a general, consistent recollection.


The testator should demonstrate a rational demeanour and coherent decision-making ability, where the decisions taken align logically with their wishes and circumstances.

Legal precepts for validity

  • The testator must be at least 18 years old, unless they are a soldier on active duty or a mariner, where exceptions can apply.
  • The will must typically be in writing and duly signed by the testator or, in specific instances, by someone else in their presence and by their direction.
  • Two impartial witnesses must observe the signing of the will and subsequently affix their signatures, confirming its authenticity and the testamentary capacity of the person making it.

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The Banks v Goodfellow Test

In evaluating testamentary capacity, the criteria is derived from the case of Banks v Goodfellow (1870). The test elucidates that a testator must:

  • Understand the act of making a will and its effects.
  • Comprehend the extent of the property being bequeathed.
  • Appreciate the claims to which they ought to give effect, discerning the potential claims and understanding the consequences of including/excluding individuals.
  • Be free from any disorder of the mind that subverts their sense of proper testamentary disposition.

The role of legal and medical practitioners

It may be necessary for medical professionals to be involved in establishing testamentary capacity, particularly where cognitive impairment or mental health disorders are apparent. When preparing the will, medical practitioners may be required to evaluate and confirm the testator’s mental state, while legal professionals ensure the procedural compliances and articulate the testator’s wishes within the legal framework.

Contentious probate and safeguarding testamentary intentions

Where testamentary capacity is contentious, and suspicions of undue influence, fraud, or incapacitation surface, probate litigation, often termed ‘contentious probate,’ can ensue. Here, the courts aim to decipher the testator’s genuine intentions, probing the circumstances surrounding the will’s creation, examining witness testimonies, and checking medical records.

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Contesting a will under testamentary capacity

You might have grounds to contest a will if there is evidence that they lacked sound mental capacity or memory during its creation or amendment. An individual must possess testamentary capacity to create or modify a will.

If you hold concerns regarding the validity of a will, specifically relating to testamentary capacity, reaching out to the experienced team at Moore Barlow LLP can be your first step towards resolution.

Contesting a will on the grounds of the testator’s mental capability necessitates a considered legal approach. Our skilled contesting a will solicitors can guide you through each stage, offering expert advice and robust support.

We understand the sensitivity and complexity that often surrounds such matters and are here to provide a transparent, empathetic, and effective service, ensuring that your concerns are thoroughly explored and addressed. Begin your journey with us to navigate through the legal intricacies and protect your interests in a potentially invalid will.

How do you prove lack of testamentary capacity?

To prove lack of testamentary capacity in the UK, evidence must indicate that the testator did not understand the extent of their estate, the beneficiaries, the significance of the will, or was subject to delusions when creating it. Medical records, witness accounts, and expert testimony are often crucial.

What is a reasonable belief of lack of capacity?

The Mental Capacity Act stipulates that, prior to acting on someone’s behalf, you must possess a reasonable belief that your assessment of their capacity is accurate. Essentially, this implies that any other reasonable individual, under identical circumstances, would arrive at a comparable conclusion to your own.

Who has to prove capacity in a will?

When a will is contested, the onus to prove testamentary capacity generally lies with the person propounding the will, meaning the individual seeking to uphold its validity. They must establish that the testator possessed the requisite mental capacity to form a valid will at the time of execution.

Can you contest a will if the person has dementia?

Yes, you can contest a will if the testator had dementia, provided you can demonstrate that they lacked testamentary capacity — an understanding of their estate and the implications of the will — at the time of its creation. Legal and medical evidence will be crucial to support the claim.

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