Mental Capacity Assessment UK (2026): MCA 2005 Two-Stage Test Explained

The Mental Capacity Act 2005 (MCA 2005) sets out a structured two-stage test that must be applied when assessing whether a person has mental capacity to make a particular decision: (1) Stage 1 — Diagnostic threshold (MCA 2005 s.2(1)): does the person have an 'impairment of, or a disturbance in the functioning of, the mind or brain'? This must be an identifiable condition — such as dementia, acquired brain injury, stroke, learning disability, mental illness (schizophrenia, severe depression, bipolar disorder), autism, or the effects of alcohol or drugs. It need not be permanent — a temporary disturbance (for example, delirium in hospital, severe intoxication, or a post-operative state) can satisfy the diagnostic threshold. Without satisfying Stage 1, there is no legal basis for concluding that a person lacks capacity; (2) Stage 2 — Functional test (MCA 2005 s.3(1)): as a result of that impairment or disturbance, can the person: (a) understand the information relevant to the decision (including the reasonably foreseeable consequences of making or not making the decision); (b) retain that information (even if only for a short time — this does not require long-term memory); (c) use or weigh that information as part of the decision-making process (including understanding risks, consequences, and alternatives); (d) communicate the decision by any means (speech, writing, gesture, augmentative communication). If the person cannot do any one of these four things as a result of the impairment, they lack capacity for that specific decision; (3) Presumption of capacity: MCA 2005 s.1(2) establishes that a person is presumed to have capacity unless it is established that they lack capacity. The burden of proof is on the person asserting incapacity — on the balance of probabilities.

There is no requirement that a mental capacity assessment under the MCA 2005 must be carried out by a doctor or specialist. The Act is deliberately broad about who can assess capacity: (1) Anyone with relevant knowledge and experience in the context of the decision: a GP can assess capacity for a simple financial or daily living decision; a district nurse can assess capacity for a medication decision; a social worker can assess capacity for a care placement decision; a solicitor or legal executive can assess capacity for a will, LPA, or property transaction; a care home manager can assess capacity for day-to-day decisions; (2) Specialist clinicians for complex decisions: for high-stakes medical decisions (major surgery, withdrawal of life-sustaining treatment), a specialist clinical assessment is expected. For decisions involving complex legal instruments (LPAs, statutory wills, Court of Protection proceedings), a formal psychiatrist or clinical psychologist assessment is often required — and expected by courts; (3) Solicitors assessing capacity for wills and LPAs: a solicitor preparing a will or LPA is expected to have reached a view on capacity before executing the document. For a will, the relevant test is Banks v Goodfellow (see below) — not the MCA 2005 functional test. For an LPA, the MCA 2005 test applies. A solicitor uncertain about capacity should refer to a medical practitioner for a formal assessment; (4) The 'assessor' does not need to be neutral: in everyday decisions, a carer, family member, or professional can assess capacity as part of their role. There is no requirement for an independent assessor unless the decision is high-stakes, contested, or involves an application to the Court of Protection; (5) Multiple assessors: different assessors may reach different conclusions — this is common in contested capacity cases. The court will weigh the evidence from all assessors.

Yes — this is one of the most important and frequently misunderstood aspects of the Mental Capacity Act 2005: (1) Decision-specific: capacity is not a global assessment. A person may have capacity to make some decisions but not others. For example: a person with moderate dementia may lack capacity to manage a complex investment portfolio (Stage 2 — cannot use or weigh complex financial information) but retain full capacity to decide where to go on holiday, what to eat, or whether to have a routine medical procedure. The assessment must always be made in relation to the particular decision at hand — not a general 'does this person have capacity?' judgment; (2) Time-specific: capacity can fluctuate over time and can improve or deteriorate. A person with a progressive condition (Alzheimer's, Huntington's) may have capacity at some times and not at others. A person in a lucid interval following delirium may have full capacity. The assessment is valid only at the time it is made for the decision at hand. MCA 2005 s.1(3) requires that all practicable steps are taken to help the person make the decision before concluding that they lack capacity — this includes: providing information in a simpler form; using visual aids or communication aids; assessing at a better time of day; having a trusted person present; waiting until a temporary impairment (medication side-effects, hospital acute illness) has resolved; (3) Practical impact: (a) for a will: the testator must have capacity at the time of giving instructions AND at the time of execution. A lucid interval can be sufficient. A solicitor should assess capacity at both points and record the assessment contemporaneously; (b) for an LPA: the donor must have capacity at the time the LPA is executed. Once capacity is permanently lost, an LPA can no longer be made — the family must apply for a Court of Protection deputyship instead; (c) fluctuating capacity: practitioners should schedule capacity assessments at the optimal time (morning for some dementia patients; not after sedating medication); document the assessment; and consider a medical opinion if there is doubt.

Two entirely separate legal tests govern mental capacity in the context of death and estate planning — and they are not interchangeable: (1) Banks v Goodfellow test (testamentary capacity — for making a will): the test established in Banks v Goodfellow (1870) requires the testator to: (a) understand the nature of making a will and its effects (that they are making a document that will dispose of their property on death); (b) understand the extent of the property being disposed of (not necessarily know the exact values, but have a general appreciation of what they own); (c) understand the claims of those who might expect to benefit (be aware of family members and others with a potential claim, even if they choose not to benefit them); (d) not be suffering from any disorder of the mind that poisons their affections, perverts their sense of right, or prevents the exercise of their natural faculties in disposing of their property. The Banks v Goodfellow test predates the MCA 2005 by 135 years and is exclusively used for will challenges. A person can satisfy the Banks v Goodfellow test but fail the MCA 2005 test, or vice versa. The MCA 2005 Code of Practice (para 4.32) explicitly states that the Act's functional test does not replace the common law Banks v Goodfellow test for wills; (2) MCA 2005 test (for LPAs, care decisions, financial decisions, other legal instruments): the two-stage diagnostic threshold plus functional test described above. This applies to LPAs, decisions about medical treatment, decisions about where to live, and most financial and legal decisions other than making a will; (3) Which applies when: Bank v Goodfellow: solely for challenges to the validity of a will on grounds of lack of testamentary capacity. MCA 2005: LPAs; statutory wills (Court of Protection); decisions made on behalf of an incapacitated person; professional obligations when taking instructions for legal documents other than wills.

Contemporaneous written records of a capacity assessment are essential — both to evidence that the assessment was properly conducted and to defend any subsequent challenge: (1) What to record: the date and time of the assessment; the decision being assessed; the two-stage test applied (diagnostic threshold + functional assessment); the specific information the person was given; how the person demonstrated understanding, retention, use/weighing, and communication; any adjustments made to assist the person (simplified information, visual aids, timing); the conclusion reached; the identity and qualifications of the assessor; (2) Best practice for solicitors executing wills: note the lucidity of the testator at the time of instructions and at execution; record the content of any medical records reviewed; record the specific questions asked to assess testamentary capacity (Banks v Goodfellow limbs); attach a contemporaneous attendance note to the will file; consider a medical opinion letter where any doubt exists; (3) When capacity is disputed: disputes commonly arise in Court of Protection proceedings (where a family member contests a decision made on behalf of someone); in probate proceedings challenging the validity of a will (testamentary capacity); in LPA registration proceedings (where an objector claims the donor lacked capacity at execution). The Court of Protection and civil courts apply the 'balance of probabilities' standard. Expert evidence (psychiatrist, neurologist, geriatrician) is often central; (4) Access to assessments: a capacity assessment document prepared by a GP or specialist for a legal purpose (such as a statutory will application) can be disclosed in Court of Protection proceedings. Medical records are frequently ordered to be produced; (5) Challenging a wrong assessment: if a person believes they have capacity but has been assessed as lacking it, they can: seek a second opinion; apply to the Court of Protection for a declaration of capacity under MCA 2005 s.15; complain to the relevant professional body; challenge a deputyship or LPA on the basis that the donor had capacity.