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Mental Capacity Act 2005

Explains how the Mental Capacity Act affects you and how you can plan ahead for when you no longer have the mental capacity to make decisions for yourself. Applies to England and Wales.

What's mental capacity?

Your mental capacity means your ability to understand information and make decisions about your life. It can also mean the ability to communicate decisions about your life.

Your capacity to make a decision can vary depending on the time that the decision needs to be made and the type of decision you need to make.

What does 'lacking capacity' mean?

If you lack capacity, this means that you’re unable to make decisions. This might be permanently, or in the short-term:

  • Permanent lack of capacity. This is where your ability to make decisions is always affected. For example, this might be because you have a form of dementia, a learning disability or brain injury.
  • Short-term lack of capacity. This means your ability to make decisions changes from day-to-day. For example, this might be because of some mental health problems, if you’re experiencing confusion as a side-effect of medication or if you’re unconscious.

Example 1

Ava has a mild form of dementia which affects her short-term memory. After she spends money, she'll often forget how much she's spent, or whether or not she's even bought anything. Her condition is unlikely to improve in the future.

Ava's capacity to make important financial decisions has been permanently affected because of her dementia.

Example 2

Paul sometimes hears distressing voices. He's generally able to do day-to-day activities, such as washing, cleaning, and cooking for himself. But when the voices are very distressing, he's not able to do these activities.

Paul's capacity to do day-to-day activities is affected in the short-term because of his mental health condition.

Different types of decisions

Whether or not you lack capacity will also depend on the type of decision that you need to make. Someone might have capacity to make more straightforward decisions, such as what to eat. But they may not have capacity for more complicated decisions. For example, whether or not they should move into a care home.

Who can assess my capacity?

Who assesses your capacity will depend on the type of decision that needs to be made.

If the decisions are for straightforward, day-to-day actions, your friends and family can assess whether or not you have capacity.

If the decisions are more difficult, such as giving consent to medical treatment, a health professional like a doctor may have to assess you.

How's my mental capacity assessed?

When someone looks at your capacity to make a decision, they must ask these questions:

  • Can you understand the information related to the decision?
  • Can you remember the information for long enough to make a decision?
  • Can you weigh up or use the information to reach a decision?
  • Can you communicate the decision in any way at all? For example, talking, using sign language or hand signals or squeezing someone’s hand?

If the answer to any of those questions is no, they'll need to consider if this is because of an illness, brain injury, a long-term coma or the effects of medication.

People should not assume that you lack capacity because of:

  • Your age
  • Your appearance
  • Any mental health diagnosis you may have
  • Any other disability or medical condition you may have

What the person assessing your capacity must remember 

  • They must begin by assuming that you have capacity
  • They must help you make a decision for yourself
  • If they make a decision for you because you lack capacity to make it yourself, it must be in your best interests. It must also restrict your freedom as little as possible
  • If you make an unwise decision, this doesn't mean you lack capacity

The same principles apply to life-changing decisions as they do to routine decisions.

Before someone can make a decision for you, they need to have a reasonable belief that you no longer have the capacity to make that decision yourself. This means asking questions like:

  • Do you have a general understanding of what decisions need to be made?
  • Do you have a general understanding of the consequences of the decision?
  • Do you show this general understanding in the way you behave and make decisions?

What happens if I'm found to lack capacity?

The Mental Capacity Act says someone else can make a decision for you if you lose your capacity to make that decision yourself. This is unless you've made a plan in advance that outlines your wishes for that decision.

Exactly who can make this decision for you will depend on the circumstances at the time. But it could be a:

  • Friend
  • Relative
  • Unpaid carer
  • Paid carer
  • Doctor
  • Social worker
  • Nurse
  • Other health care professional
  • Court 

Even if someone else is making decisions for you, you should still be involved as much as possible.

Some everyday decisions that are part of your care and treatment can be made without a professional having to assess your capacity. For example, a family member helping you get dressed or choosing what you eat.

If you want to make important decisions for someone else because they lack capacity, you may need to arrange an assessment of that person’s capacity.

If the decision you want to make has long-term or irreversible effects, you may need to get legal advice about whether the law allows you to make it. You might need to get permission from a Court of Protection.

Can mental health problems affect my capacity?

The Mental Capacity Act may apply to you if you have a mental health problem that affects your ability to make a particular decision. But any of the following may also apply:

  • You may still be able to make some of your own decisions.
  • Your capacity to make decisions may return.
  • Your capacity to make some decisions may only be affected occasionally, or for short periods of time.

This information was published in April 2023. We'll revise it in 2026.

References are available on request. If you would like to reproduce any of this information, see our page on permissions and licensing.

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