Author and Publication
Author: Nellie Supports Ltd
Publication Date: 15/05/2026
Citation
Mental Capacity Act 2005, c. 9. Available at: https://www.legislation.gov.uk/ukpga/2005/9/contents
Copywright
Copyright © 2026 Nellie Supports Ltd. All rights reserved.
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Solicitor instructions and evidence in will capacity assessments
The quality of a will capacity assessment is set by the letter of instruction. A strong instruction identifies the testator and the proposed will, encloses the draft will, previous wills and a broad estate summary, explains any changes from earlier wills and the family context, discloses known diagnoses and records, and asks the assessor to address the Banks v Goodfellow test at the date of execution. Vague instructions produce vague reports, and vague reports lose probate disputes. This guide sets out what solicitors should send, what the assessor should return and how the resulting evidence protects the will.
Why the instruction shapes the evidence
In will capacity work, the letter of instruction determines what the assessment can achieve. An instruction that asks whether the client has capacity in general invites a report answering the wrong question, because testamentary capacity is a specific legal test applied to a specific will at a specific time. Solicitors who frame the instruction around the actual will being made, and who supply the context that makes the test answerable, receive reports that protect the will; vague instructions produce vague evidence.
What the letter of instruction should contain
The letter should identify the client, the fact that a will is being made and its broad shape, the reason capacity is in question, any diagnosis or concern known to the firm, the timescale, and whether the report may later be used in contested proceedings. It should name the test to be applied, ask for the assessment to address each limb and confirm the practical arrangements: where the client will be seen, who else will be present, and whether the assessor should also attend or advise around execution.
The records and context to enclose
The assessor should not work blind. Useful enclosures include relevant medical records or a GP summary, earlier wills and any letter of wishes, a note of the estate's broad composition and value, the family structure including anyone being excluded or treated unequally, and the drafting solicitor's own attendance notes. The claims limb of the test cannot be assessed without knowing who has claims, and the property limb cannot be assessed without knowing broadly what the estate contains.
Contemporaneous assessment and the golden rule
Where the testator is elderly or seriously ill, good practice is for capacity to be assessed and recorded at the time the will is made, rather than reconstructed afterwards. A contemporaneous assessment, ideally close to both instructions and execution, is the single most effective protection a solicitor can build around a will that may be challenged. It converts the firm's file from a target into a shield, and it preserves the testator's own words at the moment they matter most.
Complex estates, unequal provision and excluded claimants
The depth of assessment should be proportionate to the will. A modest estate passing equally to children engages the test lightly. A complex estate with business interests, trusts or property abroad demands more of the property limb, and a will excluding a child, favouring a new relationship or departing sharply from earlier wills demands more of the claims limb. The instruction should flag these features expressly, because they define where the evidential weight needs to sit and where any later challenge will aim.
Timing the assessment around instructions and execution
Capacity is time-specific, and the law recognises that a testator who gave capacitous instructions may validly execute a will prepared upon them even if capacity has declined by execution, provided they understand they are executing the will they instructed. Where a client's condition is progressive or fluctuating, assessment at the point of instructions, with a shorter confirmatory check at execution, closes the gap a challenger would otherwise exploit and keeps the evidence aligned with how the will was actually made.
What the report gives the solicitor
A strong testamentary capacity report sets out the test, the sources reviewed, the practicable steps taken, the client's own explanation of their estate, their family and their reasons, the analysis against each limb and a clear conclusion. It sits on the will file alongside the attendance notes, and if the will is ever challenged, it is contemporaneous, independent, decision-specific evidence from a professional assessor, which is precisely the evidence probate disputes so often lack.
Contested contexts and CPR Part 35
Where a dispute is already live or clearly foreseeable, the instruction should say so, because the report should then be prepared to CPR Part 35 standards from the outset: the expert's overriding duty to the court, the substance of instructions stated, the range of opinion addressed and the reasoning shown in full. Upgrading a report to litigation standard after the event is far harder than commissioning it correctly, and the difference in cost at instruction is trivial against the cost of weak evidence in proceedings.
Key takeaway
The quality of will capacity evidence is decided at instruction: name the test, describe the will and the estate, disclose the family context and the concerns, enclose the records and time the assessment around instructions and execution. A solicitor who instructs this way obtains a report that protects the will, the client's wishes and the firm itself for as long as the will may ever be questioned.
Frequently asked questions
Does a diagnosis automatically mean someone lacks capacity?
No. A diagnosis may explain why capacity is in doubt, but it does not answer the legal question. The assessment must still consider the specific decision, the relevant information, the support provided and whether the person can understand, retain, use or weigh that information and communicate a decision.
What evidence is useful for Testamentary Capacity Assessment?
Send the draft will, previous wills, a broad estate summary, relevant medical records or consent to obtain them, the family and beneficiary context and any attendance notes recording earlier instructions. The assessor should confirm what was received and reviewed, because the reviewed-material list is one of the first things a challenging party examines.
When is a formal assessment for Testamentary Capacity Assessment useful?
A formal assessment is most valuable where the will departs from earlier wills or expectations, where a diagnosis raises doubt, where the estate is complex, where family conflict is foreseeable, or where the testator is elderly and the golden rule points to contemporaneous capacity evidence.
Related mental capacity assessment pages
These internal links help readers move from this guide to the most relevant Nellie Supports service page, assessment option or legal framework page.
Instructing a will capacity assessment?
Nellie Supports completes testamentary capacity assessments across England and Wales, prospective, contemporaneous and retrospective, through a permanent employed team with every report peer reviewed before delivery. Call 0333 987 5118 or visit the testamentary capacity assessment service page.