What the Latest State-Of-The-Art Research Tells Us About Good Testamentary Capacity Assessments

Dr. Olga Chelidoni
4 hours ago
4 min read

When someone makes a will, one of the most important questions is whether they had the mental capacity to make that decision at the time.

For over 150 years, the courts have relied on the legal principles established in Banks v Goodfellow (1870). These principles remain the foundation of testamentary capacity assessments today. They require a person to understand that they are making a will, the nature of their estate, the people who may have a claim on that estate, and the effect of the decisions they are making.

But while the legal test has remained largely unchanged, the science behind mental capacity assessments continues to develop.

A recent review of the Testamentary Capacity Assessment Tool (TCAT) by Voskou, Douzenis, Ekonomou and Papageorgiou (2026), published in the Journal of Dementia and Alzheimer’s Disease, highlights how researchers are working to make testamentary capacity assessments more structured, transparent and evidence-based.

Looking Beyond Memory

One of the most common misunderstandings about testamentary capacity is that it is simply about memory.

In reality, making a will is a complex decision. A person may remember their family members and know what assets they own, but still struggle with judgement, reasoning or understanding the consequences of their choices.

The researchers behind the TCAT argue that a thorough testamentary capacity assessment should consider several important abilities, including:

Memory and recall.
Understanding of financial matters.
Decision-making and judgement.
Awareness of relationships and family circumstances.

The ability to reason through situations involving trust and influence.

These findings reflect what many experienced assessors already know: capacity is rarely determined by a single answer or a single test score.

Why Structure Matters

One of the most interesting aspects of the research is its focus on structured assessment.

The TCAT uses carefully designed questions and practical scenarios to explore how a person thinks about financial decisions, relationships and everyday problems. Rather than simply asking factual questions, it encourages assessors to explore the reasoning behind a person's answers.

This approach is important because courts often need to understand not only what a person decided, but how they reached that decision.

A well-structured assessment helps ensure that important areas are explored consistently and that conclusions can be clearly explained if they are later challenged. This is one reason why choosing a suitably experienced mental capacity assessor can be so important in complex or disputed will-making situations.

Capacity Is Not the Same as Diagnosis

Another important message from the research is that a diagnosis of dementia does not automatically mean a person lacks testamentary capacity.

Many people with mild cognitive impairment or early-stage dementia continue to understand their wishes, relationships and financial circumstances well enough to make a valid will.

Equally, some people may have difficulties with judgement or decision-making that require closer examination.

This is why good assessments focus on the person's abilities rather than their diagnosis alone.

The question is not whether someone has dementia.

The question is whether they can make the specific decision that is being assessed.

The Importance of Evidence

At Nellie Supports, we believe that professional opinions should be supported by evidence.

Recent research reinforces this principle. The authors of the TCAT model emphasise that specialist assessment tools should support professional judgement, not replace it. No assessment tool can determine testamentary capacity on its own.

Instead, tools and structured interviews help assessors gather evidence, identify relevant strengths and difficulties, and explain how they arrived at their conclusions.

This is particularly important in situations where family members disagree, concerns have been raised about undue influence, or a will may later be challenged. In higher-risk or contested cases, a more detailed Enhanced Capacity Assessment Service may be appropriate where wider evidential work is needed.

What This Means for Families and Professionals

The most significant lesson from this research is not that there is a new test for testamentary capacity. It is that good assessments are becoming increasingly evidence-led.

Modern practice is moving towards assessments that are:

Structured.
Transparent.
Based on relevant evidence.
Focused on the person's actual decision-making abilities.
Capable of being explained and scrutinised.

These are principles that benefit everyone involved, including the person making the will, their family, legal professionals and ultimately the courts.

Where a person is no longer able to make or change a will themselves, families and professionals may need to consider whether a statutory will assessment package is required instead.

The Future of Testamentary Capacity Assessment

Research in this area continues to develop, particularly in understanding how memory, judgement, social understanding and vulnerability to influence affect will-making decisions.

While no single assessment can provide all the answers, studies such as these are helping professionals build more reliable and consistent approaches to evaluating testamentary capacity.

At Nellie Supports, we welcome developments that strengthen evidence-led practice and improve the quality of assessments. The goal is not simply to reach a conclusion, but to ensure that conclusions are supported by clear evidence, sound reasoning and a process that can withstand scrutiny.

Because when important decisions about a person's wishes and legacy are involved, the quality of the assessment matters.

You can also explore our wider mental capacity assessment guides for further information about decision-specific capacity.