This guide is maintained as a current resource for September 2026 and covers only the laws of England and Wales. Information is for general guidance, not legal advice. Consult a qualified solicitor for advice specific to your situation.
Learn what testamentary capacity means in England and Wales, the legal criteria under Banks v Goodfellow, how capacity is assessed, the role of medical evidence and the consequences of lack of capacity for wills and probate disputes.
Testamentary capacity is a key legal concept in wills and probate law in England and Wales. It refers to a person's mental ability to make or amend a valid will. If someone lacks the required capacity when they execute their will, the will can be invalidated by a court, potentially leading to disputes, unintended distributions under intestacy rules, and legal challenges. This article explains what testamentary capacity means under law, how it is assessed, the legal tests involved, practical considerations when someone's capacity is in doubt, and the implications for wills and estate planning. All explanations are based on up‑to‑date authoritative sources and common law principles.
What Is Testamentary Capacity?
Testamentary capacity describes whether a person (known as the testator) has the requisite mental and legal ability to understand and execute a will at the time it is signed. Capacity is a distinct legal requirement separate from the formal execution rules (such as having two independent witnesses). A will executed without capacity is at risk of being declared invalid.
In common law, capacity is not assessed by reference to general day‑to‑day decision‑making abilities. Instead, it focuses on whether the testator can understand and reflect on the specific act of making the will and its effects.
The Legal Test: Banks v Goodfellow (1870)
The legal test for testamentary capacity in England and Wales originates from the historic case Banks v Goodfellow (1870). This remains the definitive test applied by courts when assessing whether a will‑maker had sufficient capacity at the relevant time.
Under this test, a testator must satisfy the following four criteria at the time the will is made:
- Understand the nature and effect of making a will - the testator must know they are creating a legal document that disposes of their property after they die.
- Understand the extent of their assets and property - the testator should have a broad grasp of what they own and are disposing of. They do not need precise valuations, but should appreciate the general nature of their estate.
- Know who might reasonably expect to benefit - the testator must be aware of the people they ought to consider, such as close family members, dependants and others with legitimate claims.
- Be free from any disorder of the mind that would affect decisions - mental conditions or delusions that influence the will's provisions may undermine capacity.
If any one of these criteria is not met at the time the will is executed, there is a material risk the will could be successfully challenged on the grounds of lack of testamentary capacity.
Interaction with the Mental Capacity Act 2005
The Mental Capacity Act 2005 (MCA) governs capacity for many personal decisions, but it does not directly replace the Banks v Goodfellow test for wills. Courts and practitioners typically apply the common law test for testamentary capacity, though the MCA's principles of presuming capacity and performing functional assessments are relevant in related settings, such as applications to the Court of Protection for a statutory will where an individual lacks capacity.
Key Principles in Practice
Presumption of Capacity
Adults are generally presumed to have the capacity to make a will unless evidence indicates otherwise. A will that appears coherent and rational tends to strengthen this presumption. If concerns arise, the burden of proof may shift to those challenging the will after death to show the testator lacked capacity at the relevant time.
Medical and Professional Evidence
In cases where capacity is uncertain - for example, if the testator is elderly, seriously ill, or showing signs of cognitive impairment - it is advisable to seek contemporaneous medical evidence. A report from a medical practitioner, commissioned at or near the time the will is signed, can provide objective documentation of capacity and reduce the risk of later disputes. This practice is sometimes referred to as the “Golden Rule” and has been recognised in continuing legal guidance and professional practice.
Timing of Capacity
Capacity must be assessed at the time the will is signed, and in many contexts, at the time instructions are given for its preparation. If a testator loses capacity between giving instructions and execution, the will may still be valid so long as the instructions accurately reflect their intentions and they understood that they were signing the document. This principle is reflected in longstanding case law.
Practical Examples and Context
- An elderly testator with mild memory lapses may still have capacity if they understand the nature and effect of the will and its likely beneficiaries.
- A testator with a diagnosed mental health condition may still have capacity unless that condition affected the specific decisions made in the will.
- Where a will makes a significant departure from a previous estate plan (for example, unexpectedly excluding close family), evidence of capacity - such as medical assessment notes - can be particularly important to counter potential challenges.
Consequences of Lack of Testamentary Capacity
If it is established that a testator lacked capacity at the time of making a will, the document may be declared invalid. In such cases:
- A previous valid will may take effect instead.
- If there is no previous valid will, the estate may pass under the intestacy rules established by statute.
- Disputes over capacity can lead to contentious probate litigation, which can involve claims in the High Court or county courts.
Questions Often Asked
What Happens if Capacity is in Doubt but a Will Is Needed Quickly?
If there are concerns that capacity may deteriorate further, it can be appropriate to obtain urgent medical assessment and contemporaneous documentation while capacity remains intact. The formal execution requirements of a will (in writing, signed by the testator, and witnessed by two independent adults) remain essential.
Can a Court Make a Will on Someone's Behalf?
Yes. If an individual lacks testamentary capacity entirely, an application can be made to the Court of Protection for a statutory will. The court will consider the best interests of the person under the Mental Capacity Act and, if appropriate, make an order for a will reflecting what would be reasonable in the circumstances.
Key Takeaways
Testamentary capacity is a fundamental legal requirement for the validity of a will in England and Wales. The Banks v Goodfellow test remains the established common law standard, requiring understanding of the act of making a will, the estate, likely beneficiaries, and freedom from disorders of mind that distort decision‑making. Practical assessment, contemporaneous evidence, and professional support can reduce the risk of later challenge. Understanding testamentary capacity is vital for anyone preparing, advising on, or contesting wills within UK law.
