What is Testamentary Capacity?

sarah ryan
Sarah RyanAccount Manager @ Lawhive & Non-Practising Solicitor
Updated on 25th October 2023

A Will is a legally binding document that outlines your wishes regarding your money, property and possessions, including how they should be distributed after your passing. A Will can also detail arrangements for minor children, both in terms of care and finances.

When you make a valid Will, you say how your estate (such as your money, property and other assets) is distributed. When you die without a Will, there is a set of rules that must be followed in terms of how the estate is divided up.


If you're considering making a Will, or already in the process of creating one, it's essential to understand the concept of testamentary capacity and the impact it could have on your parting wishes and beneficiaries.

By the end of this article you'll have a clear understanding of what testamentary capacity is, how it is tested and the impact it can have.

What is Testamentary Capacity?

Testamentary Capacity is a person's legal ability to make or change their Will. Testamentary capacity says whether someone is mentally capable of deciding how they want their assets, property and money distributed, as well as who should take care of their children when they pass away.

If a Will appears logical and is properly signed in the presence of witnesses, it will be assumed that the person making the Will had the necessary testamentary capacity. Under these conditions, anyone challenging the Will based on capacity concerns must demonstrate that the testator lacked testamentary capacity.

If a person lacks testamentary capacity, any Will they create may not be valid in the eyes of the law.

Banks v Goodfellow

The landmark case of Banks v Goodfellow introduced the 'Golden Rule,' which assesses an individual's mental capacity and their grasp of necessary knowledge and understanding when making a Will.

Despite the introduction of the Mental Capacity Act 2005, this test continues to be relevant.

According to this test, to have testamentary capacity, a person must:

  • Understand the nature and effect of making a Will;

  • Understand what assets they have;

  • Be aware of any moral claims on their estate (like providing for family members). This involves differentiating between individuals and making a moral assessment, for instance, regarding whether a specific child should be favoured over others based on factors like their financial status, merit, familial obligations, or health condition;

  • Not be affected by any mental disorder that may influence their decisions or affect their ability to decide how to distribute their assets.

Mental Capacity Act

The Mental Capacity Act 2005 is a more recent law that addresses mental capacity in various situations, including making Wills. It sets out a clear framework for assessing a person's capacity, emphasising that any impairment of the mind or brain must be taken into account.

These standards help ensure that individuals making a Will are doing so of their own free will and that their decisions are not influenced by external factors.

The Mental Capacity Act prioritises:

  • Respect for Personal Choices: This law makes sure that people, even if they have trouble making decisions because of an illness or disability, are still allowed to make choices about their own lives as much as possible.

  • Decision-Making Support: If someone needs help to make a decision, the Mental Capacity Act says that they should get support. This could be from family, friends, or professionals. The goal is to help them make choices that are best for them.

  • Best Interests: Sometimes, a person might not be able to make decisions at all, even with help. In these cases, the law says that decisions should be made in their "best interests." This means doing what's right for that person based on what they would have wanted if they were able to choose.

  • Only Necessary Restrictions: The law also says that any restrictions on a person's freedom and choices should be as small as possible. This is to protect people's rights and not take away more freedom than needed.

How the Mental Capacity Act helps

Imagine if a family member had dementia or a brain injury, and they couldn't decide for themselves where to live or how to spend their money. The Mental Capacity Act ensures that their choices are respected, and if they need help making decisions, it's done in a way that's best for them.

The law is there to protect people's rights and ensure their voices are heard, no matter their circumstances.

Who is responsible for ensuring Testamentary Capacity?

The responsibility for ensuring testamentary capacity lies with the person creating the Will, but it's essential to seek professional advice.

Wills, trust and probate solicitors are often involved in the process to make sure everything is done correctly and within the law. They can also help assess whether you have the mental capacity to make a Will or not.

What if a person doesn't have testamentary capacity?

If a person is determined not to have testamentary capacity, it means they might not be legally capable of making or altering a valid Will.

This situation can have several important consequences:

Invalid Will

If someone is found to lack testamentary capacity when they made their Will, it may be considered invalid in the eyes of the law. This means the Will cannot be used to distribute their assets, property, and carry out their wishes.

Intestacy Rules

When a Will is declared invalid due to a lack of testamentary capacity, the person's estate (their belongings, property, money, etc.) will be distributed according to the rules of intestacy. Intestacy rules are legal guidelines that determine how an estate is divided when there is no valid Will. This distribution may not align with the person's actual wishes.

Challenges to the Will

In some cases, disputes can arise over the question of testamentary capacity. People who believe that the Will is invalid due to the testator's lack of capacity might challenge it in court. These challenges can lead to legal proceedings known as contentious probate.

If someone is concerned about a person's testamentary capacity or suspects that a Will was made when the testator lacked capacity, it's important to seek legal advice. A solicitor can guide you through the legal processes involved in addressing these issues and help determine the best course of action.

To ensure that your Will is legally valid and your wishes are carried out, it's important to create or update your Will while you have the mental capacity to do so. If you have concerns about testamentary capacity or need assistance with your Will, consulting a solicitor is a wise step to take.

Contentious probate involving Testamentary Capacity

Contentious probate involving testamentary capacity comes about when there are questions or challenges related to the mental capacity of the person who created the Will. These disputes can lead to complex and often emotionally charged legal proceedings. In these situations, the court will carefully consider the evidence and circumstances to decide whether the Will should be upheld or declared invalid.

A contentious probate involving testamentary capacity entails:

1. Challenging the Validity of a Will

Contentious probate typically begins when someone challenges the validity of a Will. This challenge can be based on various grounds, but when it comes to testamentary capacity, it means arguing that the testator did not have the mental capacity to make the Will at the time it was created.

2. Key Arguments in Contentious Probate

The key argument is whether the testator met the legal requirements for capacity when the Will was made. This often involves looking carefully at the circumstances under which the Will was created.

3. Evidence and Expert Opinions

Those challenging the Will may present evidence that the testator had a mental disorder or lacked the required understanding to make a Will. Witnesses, medical records, and expert opinions may be presented to support these claims.

4. Court Proceedings

The court will carefully evaluate all the evidence and arguments presented by both sides. The judge will ultimately decide whether the Will is valid or should be declared invalid due to a lack of testamentary capacity.

If the court determines that the Will is valid and that the testator had testamentary capacity, the estate will be distributed according to its terms. However, if the court finds that the testator lacked capacity when making the Will, it will be declared invalid. In such cases, the estate may be distributed according to the rules of intestacy, unless there is a prior valid Will.

Contentious probate cases can be emotionally challenging for all parties involved. They often pit family members and loved ones against each other, making an already difficult time even more distressing.


Remember, writing a legally binding Will is the only way to make sure that your wishes are carried out regarding your assets, property, money, and even childcare after you've passed away. It's also essential to act sooner rather than later. Waiting until you're older or have significant health issues can lead to complications regarding testamentary capacity.

If you need help with your Will, whether you're creating a new one, updating an existing will, or facing challenges with a will, you don't have to navigate this process alone. Our team of expert wills, trust, and probate solicitors is available to assist you with fixed fees. Tell us about your case, and we'll help you get started today.

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