ARTICLE
7 July 2025

Testamentary Capacity: Key Legal Principles For Will Validity

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Anthony Gold Solicitors LLP

Contributor

Anthony Gold Solicitors are a leading Law firm based in London. Our solicitors specialise in various areas of law and are experts in their fields of legal services. We are negotiators and litigators, committed to doing whatever is best for our clients.
The loss of a loved one is always challenging, and discovering unexpected changes in their will can add to the distress. It can be even more troubling if the will seems out of character, perhaps made shortly...
United Kingdom Family and Matrimonial

The loss of a loved one is always challenging, and discovering unexpected changes in their will can add to the distress. It can be even more troubling if the will seems out of character, perhaps made shortly before their death or during a period of illness.

Perhaps the terms of the will do not make sense – they may have left their estate to a charity which they have no connection to, or maybe they left their estate entirely to one family member or to a complete stranger.

In some cases, a will can be declared invalid if the person making it (the testator) did not fully understand the document they were preparing and signing, or in other words did not have "testamentary capacity". It is possible to ask the Court to set aside an invalid will in favour of an earlier valid will or, if there is no earlier will, the intestacy rules.

There can be a number of reasons why a testator would lack testamentary capacity, but some common reasons can include a diagnosis of advanced dementia, learning difficulties, mental health conditions, or urinary tract infections in older people.

However, the mere fact someone has dementia or another health condition at the time they made their will does not automatically mean that they lacked testamentary capacity, and their will is invalid. Similarly, it is possible for an otherwise perfectly healthy person to lack testamentary capacity, for instance if they were suffering a severe grief response or extreme stress at the time they made their will.

Testamentary Capacity

The test for whether someone has capacity to make a valid will is set out in the 1870 case of Banks v Goodfellow, which the Courts continue to apply today. According to Banks, a testator will only have testamentary capacity when it can be shown, at the time of giving instructions to make the will, they:

1. Understand the nature and act of making a will and its effects

This requirement relates to the capability to understand what a will does generally, and the capability to understand the specific will the testator is making. In other words, it is possible for someone to be capable of understanding the nature and effect of a simple will, but not a very complicated one.

It is not necessary to prove that the testator actually has this understanding, just that they are capable of doing so.

2. Understand the extent of their estate of which they are disposing by will

This requirement is relatively self-explanatory; a testator should generally be able to understand what property or assets are in their estate. However, it is not necessary for a testator to understand the precise value of their assets or their estate as a whole.

3. Understand and appreciate any claims against their estate, and

A testator should be capable of understanding who could make a claim against their estate if they exclude them from their will. For example, if a married testator decides to exclude their younger spouse or minor children from their estate, they must understand that they would have a claim for a share of inheritance under the Inheritance (Provision for Family and Dependants) Act 1975.

If a testator understands this but nonetheless chooses to exclude their spouse or children from their will, it does not mean that the will is invalid.

4. Not suffer from any 'disorder of the mind' such as to impair or influence the above factors.

As set out above, a 'disorder of the mind' is considered any sort of permanent or temporary health condition that affects a testator's testamentary capacity. This can include, but is not limited to: advanced dementia, urinary tract infections (particularly in older people), learning difficulties, delusional thoughts, or an extreme reaction to stress or grief.

A testator may have a 'disorder of the mind' that does not affect their capacity to make a will or similarly may lack a 'disorder of the mind' but still be incapable of making a will.

Practical steps to take when making a will

Whilst not required, it is strongly recommended that you seek legal advice from a regulated firm of solicitors when making your will. At the time of taking your instructions, your solicitor should ask you questions to assess your understanding.

Where there are possible doubts about your testamentary capacity, it is best practice for your solicitor to arrange a formal assessment by a doctor and to have the same doctor witness your will. If your solicitor does this, do not be offended – it is a worthwhile step that can drastically reduce the prospect of a successful challenge to the validity of your will after you pass away.

When taking your instructions and overseeing the execution of your will, your solicitor should make detailed notes of your instructions and their assessment of your capacity. A full and accurate file which includes a detailed attendance note from your solicitor will make it more difficult for others to successfully challenge the validity of your will.

Proving testamentary capacity after death

Currently, the burden of proving a testator's capacity to make a particular will lies with the person who wants the will to be upheld. However, in cases where the will appears rational on its face and is correctly executed, the Court will presume that the testator had testamentary capacity. If a person wants to challenge the validity of a will, the burden of proof then shifts to them, where they must raise a "real doubt" about the testator's capacity. Where a real doubt can be raised, the burden then shifts back to the person upholding the will to establish the testator's capacity.

The shifting burdens of proof can make the process of disputing or defending the validity of a will on the basis of testamentary capacity very cumbersome and expensive. Increasingly, Courts are taking a more holistic approach to assessing a testator's capacity based on assessing the evidence as a whole, but this is not being consistently applied.

Potential reform to the law of testamentary capacity

The Law Commission has recently released a report on reforming the law relating to wills. One of their recommendations is to change the test of testamentary capacity to that set out in the Mental Capacity Act 2005. The Law Commission have also suggested that the criteria in Banks is retained in accompanying guidance to the Mental Capacity Act when assessing a testator's testamentary capacity.

The Mental Capacity Act 2005 contains a statutory presumption of a person's capacity unless it can be established on the balance of probabilities that they do not have capacity. The proposal to include testamentary capacity within the scope of the Mental Capacity Act should make the process of proving or disproving capacity more straightforward but would not fundamentally change the outcome of most post-death disputes.

However, the proposed reforms would allow a testator who may lack testamentary capacity without additional support to make a valid will if they are offered that support. This would, at least in theory, allow people who may otherwise be unable to make a valid will, to do so without resorting to the appointment of a deputy and applying to the Court of Protection for a statutory will.

It remains to be seen whether the Government will adopt all or any of the recommendations made by the Law Commission, whether Parliament passes a new Wills Act containing those recommendations, and how the reforms will work in practice.

Practical steps when you want to dispute or defend the validity of a will

We would recommend seeking independent legal advice as soon as possible when you are faced with a potential will validity dispute after the death of a loved one.

However, there are several steps you can take immediately to protect your position and potentially strengthen your case if the dispute proceeds to Court:

Disputing a will

If a Grant of Probate has not already been obtained and you are not the executor of the testator's estate, you may wish to consider entering a "caveat". A caveat will prevent the executor(s) of the testator's estate from obtaining a Grant of Probate and distributing the estate to allow you sufficient time to investigate the disputed will.

You can enter a caveat online for a fee of £3.00. A caveat lasts for 6 months but can be renewed as many times as necessary or removed voluntarily at any time. However, a caveat can be removed by the executor(s) and there are potential costs consequences to you if this happens, especially if you do not benefit under a previous will of the testator or the intestacy rules.

You should try to preserve as much evidence as you can; text messages, letters, emails, greetings cards from the testator can all be helpful in establishing capacity. You should also find out the name of the testator's General Practitioner and request copies of their medical records. You may wish to contact other family members or friends of the testator to see if they would be willing to provide witness evidence.

If you are aware of any earlier will(s) that were prepared by the testator, you should try to obtain copies of these and provide them to your solicitor. You may be able to write to the solicitor or will-writer who prepared these will(s) to request them, although they will require permission from the executor(s) to release them to you. You should also find out the name of the solicitor or will-writer that prepared the disputed will.

Defending a will

If you are an executor of a will that is being disputed, and someone asks you to provide information about the will, the estate, or testator, it is important that you are reasonable when dealing with any requests. It is important that you follow the advice of your solicitors, because if you are found to have acted in an unreasonable manner by refusing to provide information, you could be ordered to pay costs.

If you are satisfied that the will is valid, you owe a duty to the beneficiaries of the will to administer the estate and distribute it to them. If someone is preventing that from happening by maintaining a caveat and fails to set out their reasons for challenging the will or fails to progress their investigations in a timely manner, you may be able to take steps to try and remove the caveat.

If you are also concerned about the validity of the will, you should not try and prove the will. You should conduct your own investigations into the validity of the will to ensure that the last valid will is admitted to probate.

If you are a beneficiary of a will that is being disputed, you should also seek independent legal advice from a solicitor, but you are also encouraged to gather your own evidence in response to any claim brought against you.

Conclusion

Anthony Gold Solicitors' Will, Trusts and Estates and Contentious Probate departments are highly experienced in all matters of estate planning and challenging the validity of wills for lack of testamentary capacity.

In today's evolving legal landscape, it's crucial to take proactive steps to ensure your wishes are respected and to stay informed about the law of testamentary capacity. If you are already faced with a will validity dispute, acting now will ensure you can protect your position and obtain sound legal advice on resolving any disputes as efficiently as possible.

The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.

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