Power of Attorney and Mental Capacity

A lasting power of attorney has to be made while you still have mental capacity. Once capacity is lost, it is generally too late to make one, and the family may have to apply to the Court of Protection instead. That single rule is the reason so much later-life planning turns on doing it early.

Mental capacity is the ability to understand and make a particular decision at the time it needs to be made. A lasting power of attorney (LPA) lets you choose who acts for you if that ability goes, but it only works if it is set up in advance. This guide explains how the two connect in England and Wales, what the law expects, and what happens if the moment is missed. It forms part of our wider estate planning guide, and sits alongside our fuller note on the Lasting Power of Attorney Explained. Figures are current as at July 2026 and are subject to change.

How power of attorney and mental capacity connect

They connect through timing. You must have mental capacity to make a lasting power of attorney, and the whole point of the document is to plan for a future in which that capacity may be reduced or gone (gov.uk, as at July 2026, subject to change). An LPA made in good time sits ready; if capacity is already lost, the door to making one has usually closed, and a different, court-based route applies.

What does mental capacity mean?

Mental capacity is the ability to make a specific decision at the moment it needs making. Under the approach set out by government guidance, a person has capacity if they can understand the relevant information, remember it long enough to decide, weigh up the options, and communicate their choice in any way (gov.uk, checking mental capacity, as at July 2026).

Two points matter. Capacity is decision-specific, so someone may be able to make some decisions but not others, and it is time-specific, because it can come and go, for example with dementia or some mental illnesses (gov.uk, as at July 2026). A person is assumed to have capacity unless it is shown otherwise, and they should be given all reasonable help to decide before anyone concludes they cannot (gov.uk, making decisions, as at July 2026).

What happens if capacity is lost before an LPA is made?

If someone loses mental capacity without a valid LPA in place, family members usually cannot simply step in to manage money or make welfare decisions. Instead, someone generally has to apply to the Court of Protection to be appointed as a deputy, a process that tends to be slower, more expensive and more closely supervised than an LPA (gov.uk, becoming a deputy, as at July 2026, subject to change). This is the situation planning ahead is meant to avoid.

The costs illustrate the difference. Applying to become a deputy carries a £421 application fee, with a further £100 assessment fee for a new deputy, and ongoing annual supervision fees of £320 for general supervision or £35 for minimal supervision in some smaller property and affairs cases (gov.uk, deputy fees, as at July 2026, subject to change). Our note on deputyship covers the route in more detail.

Apply to the court. A proposed deputy applies to the Court of Protection with supporting evidence about capacity (gov.uk, as at July 2026).
Pay the fees. A £421 application fee applies, plus a £100 assessment fee for a new deputy (gov.uk, as at July 2026, subject to change).
Ongoing supervision. Deputies are supervised and pay an annual fee, £320 for general supervision or £35 for minimal supervision in some cases (gov.uk, as at July 2026, subject to change).

	Lasting power of attorney	Deputyship
When it is set up	While the donor still has mental capacity	After capacity has been lost
Who chooses the attorney/deputy	The donor chooses their attorneys	The Court of Protection decides who is appointed
Where it is registered	Office of the Public Guardian	Court of Protection appoints; OPG supervises
Typical cost	£92 to register (reductions may apply)	£421 application, £100 assessment, then annual supervision
Ongoing supervision	Generally none by default	Supervised, with an annual fee

Sources: gov.uk/power-of-attorney and gov.uk, deputy fees, as at July 2026 and subject to change.

A worked example (illustration only). Two siblings each plan differently. One parent makes a property and financial affairs LPA and a health and welfare LPA while well, paying £92 to register each with the Office of the Public Guardian (gov.uk, as at July 2026, subject to change). The other parent makes nothing and later loses capacity after a stroke. That family has to apply for deputyship, meeting a £421 application fee, a £100 assessment fee, and annual supervision of £320 (gov.uk, as at July 2026, subject to change), on top of a wait for the court. Every case differs and the figures change, so this is general information rather than a calculation for any real family.

Making decisions once an LPA is in use

An attorney does not get a free hand. When acting for someone who lacks capacity, an attorney or deputy must support the person to make their own decision where possible, act in that person's best interests, and choose the option that restricts their rights and freedom as little as possible (gov.uk, making decisions, as at July 2026). These duties sit at the heart of how powers are meant to be used, and they apply whether the authority comes from an LPA or from the court.

The document names who can act. The law still decides how they must act, generally in the person's best interests.

When many people choose to put an LPA in place

There is no set age. Because capacity can be lost suddenly through accident or illness, as well as gradually, many people choose to make an LPA alongside a will rather than waiting for a health scare. Common prompts include a diagnosis, a milestone birthday, taking on a mortgage, or simply reviewing wider arrangements. Starting while clearly well tends to keep the choice of attorney firmly in the donor's own hands.

Alongside making or updating a will
After a diagnosis that may affect capacity over time
On reaching a milestone age or retirement
When one partner has generally handled the finances

Mental capacity and attorneys in Scotland and Northern Ireland

This guide describes the law of England and Wales, where the lasting power of attorney and the Court of Protection apply, and an LPA is legally binding only in England and Wales (gov.uk, as at July 2026, subject to change). Scotland has its own system of continuing and welfare powers of attorney, registered with the Office of the Public Guardian (Scotland), with guardianship where capacity is already lost. Northern Ireland has separate arrangements again. If matters cross a UK border, it can be worth taking advice in each nation.

Frequently asked questions

Can you get power of attorney for someone who lacks mental capacity?

Generally no. A lasting power of attorney has to be made by the person themselves while they still have mental capacity to understand it (gov.uk, as at July 2026, subject to change). Where someone has already lost capacity, a family member or other suitable person usually has to apply to the Court of Protection to be appointed as a deputy instead, which is a separate process.

What does mental capacity mean for a power of attorney?

It means being able to understand and make the decision to create the LPA at the time it is signed. Under government guidance, a person has capacity if they can understand relevant information, retain it long enough to decide, weigh up the options, and communicate a choice (gov.uk, checking mental capacity, as at July 2026). Capacity is decision-specific and can change over time.

How much does it cost to register a lasting power of attorney?

Registering an LPA with the Office of the Public Guardian currently costs £92, unless you qualify for a reduction or exemption (gov.uk, as at July 2026, subject to change). Each type of LPA is registered separately, so making both a property and financial affairs LPA and a health and welfare LPA generally means two fees. Reductions may apply on lower incomes.

What if my relative has already lost capacity?

Where capacity is already gone and no LPA exists, someone usually applies to the Court of Protection to become a deputy. That involves a £421 application fee, a £100 assessment fee for a new deputy, and annual supervision of £320 or, in some smaller cases, £35 (gov.uk, as at July 2026, subject to change). It can be worth discussing the options with a qualified professional.

When can a health and welfare LPA be used?

A health and welfare LPA can only be used once it is registered and the donor is no longer able to make the relevant decisions themselves (gov.uk, as at July 2026, subject to change). By contrast, a property and financial affairs LPA can be used as soon as it is registered, with the donor's permission, so the two types work to different timings.

Does an English LPA work in Scotland or Northern Ireland?

An LPA made under the law of England and Wales is legally binding only in England and Wales (gov.uk, as at July 2026, subject to change). Scotland uses continuing and welfare powers of attorney registered with its own Office of the Public Guardian, and Northern Ireland has separate rules. If your affairs cross a UK border, it can be worth taking advice in each relevant nation.

About Fairchild Oldfield

The Fairchild Oldfield team brings together estate planning, tax, independent financial advice and client care, working with families across England and Wales.

Fairchild Oldfield are estate planning specialists and will writers, not a firm of solicitors. This article is general information based on practical experience, not legal, tax or financial advice.

Important: This article is general information only and is not legal, tax or financial advice. Reading it does not create a professional relationship. It is based on the law of England and Wales, and other UK jurisdictions may differ. Figures and rules are current as at July 2026 and are subject to change. Before acting, many people choose to seek advice from a suitably qualified professional, such as a solicitor, a STEP practitioner, an accountant, or an FCA-authorised financial adviser, who can consider your individual circumstances.