Elderly careLegal

Mental capacity, and how it is assessed

Mental capacity is not something a person simply has or does not have. It is judged one decision at a time, on the day that decision has to be made, and the law starts by assuming your parent can make it. Here is the test an assessor uses, who carries it out, what happens if your parent cannot decide, and what to do if you think the professionals have it wrong.

By James Bowdler, founder of PrimeCarers  ·  Updated September 2026  ·  10 min read · See what the test asks

Part of our guide to elderly care.

One decision at a time

Capacity is judged for one decision, on the day it has to be made

The Act does not ask whether your parent is capable in general. It asks whether they can make this particular decision at this particular moment, which is why the answer can differ for two decisions on the same afternoon.

Section 2 of the Mental Capacity Act 2005 says a person lacks capacity in relation to a matter if, at the material time, they are unable to make that decision because of an impairment of, or a disturbance in the functioning of, the mind or brain. The phrases that matter to a family are "in relation to a matter" and "at the material time". Capacity is worked out separately for each decision, and it can be there in the morning, gone by the evening, and back again.

What to eat, and who comes into the house

What deciding it takes
Understanding the choice in front of them and saying which they want.
How it is judged
Somebody well into dementia can still make choices like these, and needing help is not a reason to take them away.

Accepting carers three mornings a week

What deciding it takes
Understanding what the visits involve, what they cost and what happens if nobody comes.
How it is judged
Assessed by whoever proposes the arrangement, usually a social worker, with the family part of the conversation.

Selling the house or changing a will

What deciding it takes
Understanding what they own, who has a claim on it, and what the change would mean.
How it is judged
Has its own legal test, and a written assessment is usual because it may be looked at years later.

Based on sections 2 and 3 of the Mental Capacity Act 2005. An assessment carried out during a hospital admission does not settle what your father can decide six weeks later at home.

A chest infection, dehydration, a new painkiller or the days after an anaesthetic can leave an older person confused enough to fail the test for a serious decision, and then lift. That is one reason the Act asks whether the decision can wait. If confusion comes and goes over months rather than days, at what point should someone with dementia go into care? follows the same judgement, and the legal side of caring for a parent sets capacity beside power of attorney, deputyship and safeguarding.

The test itself

The two questions an assessment has to answer

One test runs through all of this. An assessor has to answer both of these questions about the decision in front of them.

Question one, from section 2

Is there an impairment of, or a disturbance in the functioning of, their mind or brain?

That covers dementia, a stroke, a brain injury, a learning disability and a severe mental illness. It also covers temporary states, such as delirium during an infection, the hours after an anaesthetic, or heavy sedation.

Worth knowing

Age, appearance, a diagnosis on its own, or behaviour that leads other people to make assumptions are not enough to establish this on their own.

Question two, from section 3

Because of that, are they unable to do any one of these four things for this decision?

All four have to be possible for the person to be treated as able to decide. The assessor works through them with the decision itself in front of them, not with a general impression of how your parent has been lately.

  • Understand it

    Take in the information that matters for this decision, explained in whatever way suits them best: simple language, in writing, in pictures, or a bit at a time.

  • Retain it

    Hold on to it long enough to make the decision. Being able to keep it in mind for only a short while does not by itself mean they cannot decide.

  • Weigh it up

    Use the information and balance it against their own situation and what matters to them, rather than repeat it back.

  • Communicate it

    Get their answer across by any means at all, including writing it, pointing, squeezing a hand or blinking.

Worth knowing

The information that matters includes what is reasonably likely to happen if they decide one way, the other way, or not at all.

Where the two answers lead

All four, for this decision

They have capacity to make it, so the decision is theirs. That includes a decision their family and their doctor all think is the wrong one.

Not all four, because of the impairment

They lack capacity for this one decision, and it has to be made in their best interests by whoever is proposing it.

Both questions have to be answered yes, and the inability has to follow from the impairment rather than sit alongside it. The question is settled on the balance of probabilities, for this decision, at the time it has to be made. A different decision next month is a fresh question.

The second question comes from section 3, and it is worth noticing what it leaves out. It does not ask whether the choice is sensible, whether the family agrees, or whether your mother could explain her reasoning to a stranger. Section 3 also says a person is not to be regarded as unable to understand something if they can understand an explanation given in a way that suits them.

Section 2 adds a protection that is easy to overlook when a family is worried. A lack of capacity cannot be established merely by reference to a person's age or appearance, or to a condition of theirs or an aspect of their behaviour that might lead others to make unjustified assumptions about their capacity. Hoarding, a raised voice and a diagnosis are not findings. The Mental Capacity Act Code of Practice is the statutory guidance professionals must have regard to, and SCIE's guidance on assessing capacity shows how social care staff apply it.

Who carries it out

Who assesses capacity, and when to ask for a formal assessment

There is no single official assessor and nothing to book. Whoever has to make or propose the decision assesses capacity for it, so different people assess different decisions about the same parent.

A day-to-day decision

A carer helping your mother decide whether to have a bath judges capacity for that, in the moment, and records anything that concerned them.

Whoever is there at the time

Treatment or an examination

The doctor or nurse recommending it has to satisfy themselves your parent can consent, each time. In a hospital the wider team may be involved, but the professional responsible for the treatment has to make sure capacity was assessed.

The clinician proposing it

A care package, a move or a care home

Whoever proposes the arrangement assesses capacity for it, usually alongside a care needs assessment. Ask to be in the room, and ask for the reasons in writing.

The social worker or the ward

A will, a power of attorney or a court form

These carry their own legal tests, and a written assessment is normal because the document may be challenged later.

A solicitor, with a doctor where there is doubt

More complex decisions are likely to need a professional opinion, and one can be asked for at any point. The Code of Practice suggests a psychiatrist, a psychologist, a speech and language therapist, an occupational therapist or a social worker, and it is clear that the professional advises while the judgement stays with the person proposing the decision. Start with the GP, who knows your parent and can refer on to a memory clinic. An assessment carried out as part of NHS treatment or a council care needs assessment costs your family nothing. A capacity assessment for a deputyship application is different, because a doctor completes a court form and practices set their own charge: what a deputyship application costs goes through the fees.

Whoever assesses should be able to say which decision they assessed, what your parent could and could not do, and why. Ask for a copy, because a second opinion or a court starts from that record. GOV.UK's guide to checking mental capacity puts the questions in plain terms.

Support and unwise decisions

Helping them decide, and why an unwise decision is not incapacity

Two of the Act's five principles do most of the work in an ordinary family disagreement. Nobody is to be treated as unable to decide until all practicable steps to help them have been tried, and nobody is to be treated as unable to decide merely because they make an unwise decision.

Steps that have to be tried first

  • The time of day when they are at their clearest, and another day if the decision can wait
  • Hearing aid in, glasses on, television off, one person talking rather than three
  • One piece of information at a time, with the main points written down for them to keep
  • Treating an infection or dehydration first, then assessing again
  • Somebody they trust, or an advocate, to help them say what they think

Not evidence that capacity has gone

  • Choosing to stay in a cold, cluttered house rather than move somewhere safer
  • Refusing carers you are certain they need
  • A diagnosis of dementia, a stroke or a mental illness on its own
  • Being frail, forgetful in conversation or hard to persuade
  • Giving a reason you find unconvincing, or refusing to give one

This is the most useful thing to hold on to when somebody tells you your father is making a terrible choice. The law protects an unwise decision as firmly as a sensible one, and the question an assessor answers is how he is deciding rather than what he decides. A run of decisions that are all out of character is a reason to look more closely rather than a finding in itself. Where somebody appears to be pressuring or frightening your parent into those decisions, the council's safeguarding team is who to tell.

If your parent has capacity and is refusing help you want them to have, this is a conversation rather than a legal question. How do you get someone to accept care? goes through what tends to work, and can an elderly person be forced into care in the UK? covers what a hospital or a social worker can require.

If they cannot decide

Best interests decisions, and who has to be consulted

Once an assessment finds your parent cannot make a particular decision, somebody has to make it for them, and section 4 of the Act sets out how. It is not a family vote, and being next of kin does not settle it.

The decision-maker is whoever proposes the act: the clinician for treatment, the social worker for a care arrangement, the carer for something in the moment. If your parent made a lasting power of attorney while they could, the attorney holds legal authority over the decisions it covers, and a deputy appointed by the Court of Protection holds it where there is no attorney. Everyone else is consulted rather than deciding, and where the decision is about money, what an attorney is allowed to spend it on sets out the duties that come with that authority.

Who must be consulted, where it is practical and appropriate

Anyone they named
Somebody your parent asked to be consulted about decisions like this one, while they could still say so.
Anyone caring for them
Family, a partner, a friend or a paid carer engaged in their care or interested in their welfare.
An attorney
Somebody appointed under a lasting or enduring power of attorney, over the decisions that power covers.
A deputy
Somebody the Court of Protection appointed because there was no power of attorney in place.

Section 4 also says what to weigh: whether your parent is likely to regain capacity and the decision can wait, their past and present wishes and feelings, anything they wrote down while they could, and the beliefs and values that would have influenced them. It tells the decision-maker to permit and encourage your parent to take part as fully as they can. Alongside it sits the fifth principle, that the purpose should be achieved in whatever way is least restrictive of their rights and freedom. Carers at home three times a day is less restrictive than a care home, so it has to be weighed rather than dismissed.

When you are consulted, you are being asked what you know of your parent's wishes, beliefs and values, not what you would do in their position.

Where the decision is who comes into the house, keep that choice as close to their own as it can be. You can search for carers near you and compare their rates and read the profiles together wherever your parent can take part. Carers on PrimeCarers charge £18 to £25 an hour with our fee included, against £28 to £35 through an agency. Every carer on PrimeCarers has had their identity and right to work checked, holds an enhanced DBS on the Update Service and has interviewed online, and they are insured while they work. Experience, training and references are their own account on their profile, so ask about those directly.

There is one more thing to know if care at home becomes intensive. An arrangement can go far enough to amount to a deprivation of a person's liberty, where somebody who cannot consent to it is under continuous supervision and not free to leave. In a care home or hospital that is authorised under the Deprivation of Liberty Safeguards. At home it has to be authorised by the Court of Protection, so take legal advice if that sounds like your position.

If you disagree

What to do when you disagree with the assessment or the decision

You can challenge both the finding that your parent lacks capacity and the decision made on their behalf. The Code of Practice sets out an order to work through, and the court comes last.

  1. 1

    Ask the assessor to explain

    First
    Ask for their reasons for believing your parent cannot make this decision, and for the evidence behind them. They should be able to show how they applied the principles of the Act. Ask in writing, and name the decision.
  2. 2

    Ask for a second opinion

    If the reasons do not hold up
    The Code of Practice says it may be possible to get a second opinion from an independent professional or another expert in assessing capacity. Say what you think was missed: a better time of day, a hearing problem, an untreated infection, or a question your parent could not follow.
  3. 3

    Ask for a best interests meeting

    Where the disagreement is about the decision
    A meeting with everyone present, including your parent wherever possible, is the ordinary way these are settled. Ask for the options in plain terms, for your parent's past wishes to be recorded, and for the least restrictive option to be weighed.
  4. 4

    Bring in an advocate, mediation or a complaint

    Before any court
    An advocate speaks for your parent. Mediation can settle a disagreement between family members, or with a care team, without going to court. Every NHS body and council has a complaints procedure, and using it puts your objection on the record.
  5. 5

    Apply to the Court of Protection

    Last resort
    The court can rule on whether your parent has capacity for a decision, decide what is in their best interests, appoint a deputy and authorise a deprivation of liberty. It costs money and takes time, and some disagreements can only be settled there.

Where the disagreement is inside the family rather than with the professionals, when siblings disagree about a parent's care covers ground a best interests meeting cannot. If money is part of it, how local authority funding works explains what a council will and will not pay for.

This page is general information about the law in England and Wales rather than legal advice. Where a decision is already in dispute, speak to a solicitor who does Court of Protection work.

Questions

Questions families ask about capacity assessments

Whoever is proposing the decision. For an everyday choice that is the person there at the time, such as a carer or a family member. For treatment it is the clinician recommending it. For a care package or a move it is usually the social worker. For a will or a power of attorney it is the solicitor, who should get a doctor's opinion if there is doubt.

Yes, and a GP is usually the right place to start, because they know her history and can refer on to a memory clinic. An assessment carried out as part of NHS care or a council care needs assessment costs your family nothing. A doctor completing the court form for a deputyship application is separate work, and practices set their own charge for it.

No. The Act says a lack of capacity cannot be established merely by reference to a person's age or appearance, or to a condition of theirs. Capacity is assessed for each decision separately, so somebody living with dementia may be unable to manage their finances while remaining able to decide where they live, who visits and what they eat.

Not if she has the capacity to make it. The third principle of the Mental Capacity Act says a person is not to be treated as unable to make a decision merely because they make an unwise decision, and that protects a choice her family and her doctor all disagree with. What justifies a closer look is how she is reaching it: whether she can take in the information, hold it, weigh it up and tell you what she has decided.

Start by asking the assessor for their reasons and the evidence behind them, in writing. If that does not settle it, the Code of Practice suggests a second opinion from an independent professional or another expert in assessing capacity, then a best interests meeting, an advocate, mediation or the organisation's complaints procedure. If it cannot be resolved, you can apply to the Court of Protection, which can rule on whether your parent has capacity for that decision.

If you need help at home

Start with our guide to elderly care

Guides for older people and their families. What it costs, what a carer does day to day, and how to hire one directly.

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