The phrase people reach for is "I'm her next of kin". It is said to bank staff, to ward sisters, to care home managers, and it very rarely achieves what the person saying it expects. Next of kin is a useful label for who to telephone. It is not a legal authority to move money, sell a house, or decide where someone lives.

The document that does grant that authority is a lasting power of attorney, and it has one unforgiving feature: it can only be made by someone who still has the mental capacity to make it. Once capacity has gone, the door closes and the family is left with a slower and much more expensive route through the Court of Protection.

What the document actually does

A lasting power of attorney is a legal document that lets you appoint one or more people — your attorneys — to help you make decisions, or to make decisions on your behalf. GOV.UK guidance on lasting powers of attorney sets out that this gives you more control over what happens to you if you lose the ability to make your own decisions, whether through illness, an accident or a condition such as dementia.

You must be 18 or over, and you must have mental capacity at the time you make it. Your attorney must also be 18 or over, and an attorney appointed for property and financial affairs must not be bankrupt or subject to a debt relief order.

There are two of them, and they are not interchangeable

This is the point most often got wrong. There are two separate types, and making one does not make the other.

  • A property and financial affairs LPA covers money, bank and building society accounts, bills, pensions, benefits and selling or buying property. It can be used as soon as it is registered, with the donor's permission, which is why it is often the more practically useful of the two.

  • A health and welfare LPA covers daily routine such as washing, dressing and eating, medical care, moving into a care home, and life-sustaining treatment. It can only be used once the donor has lost the mental capacity to make those decisions themselves.

Families frequently make the financial one, assume the care decisions are covered, and discover otherwise at the worst moment. Most people who make one should think seriously about making both.

Registration is the step that counts

An LPA has no effect until it is registered with the Office of the Public Guardian. GOV.UK guidance on making a lasting power of attorney explains that the document must be signed by the donor, by a certificate provider who confirms the donor understands what they are doing and is not under pressure, and by the attorneys — in that order, with witnesses.

Applying to register costs £92, unless a reduction or exemption applies, and registration takes around eight to ten weeks if there are no mistakes in the application. Mistakes are common and are the usual reason for delay, which is another argument for doing it long before it is needed.

The Office of the Public Guardian is a government body, and its published role includes supervising deputies, maintaining the registers of powers of attorney, and investigating concerns about how an attorney is behaving.

Attorneys are not free to do as they please

An attorney is not a beneficiary in waiting. Anyone making decisions for another person under the Mental Capacity Act 2005 must act in that person's best interests, must start from the assumption that the person can make their own decisions, and must help them to make as many of their own decisions as possible. GOV.UK guidance on making decisions for someone else sets out those duties, and the Mental Capacity Act code of practice explains them in detail.

In practice this means keeping the person's money separate from your own, keeping records, and not making gifts beyond what the document and the law allow. Attorneys who fall short can be investigated and removed.

Choosing the people

The legal test is simple and the human judgement is not. An attorney should be someone you trust with your money and your comfort, who is likely to outlive your need for them, and who can handle administration without falling out with the rest of the family.

Appointing more than one attorney forces a further choice: jointly, meaning every decision must be made together, or jointly and severally, meaning any one of them can act alone. Jointly sounds safer and is often the cause of paralysis when one attorney is abroad or unwell.

Different rules elsewhere in the UK

Scotland has its own regime. Powers of attorney there are registered with the Office of the Public Guardian (Scotland), and mygov.scot guidance on power of attorney explains the continuing (financial) and welfare varieties and how to register them.

Northern Ireland has not adopted the lasting power of attorney at all. As nidirect guidance on managing your affairs and enduring power of attorney explains, an enduring power of attorney is used instead, and it covers property and financial affairs rather than health and welfare decisions.

If it is already too late

Where someone has already lost capacity and no LPA exists, the family cannot make one retrospectively. The route is an application to be appointed as a deputy by the Court of Protection, which is slower, supervised and considerably more expensive. That is the whole argument for doing this early, in the ordinary run of life, alongside the will.

Fact check

The absence of any legal authority attaching to the phrase "next of kin", and the requirement that a lasting power of attorney be made while the donor still has mental capacity, were checked against GOV.UK guidance on lasting powers of attorney and against the Mental Capacity Act 2005 code of practice.

The two types of lasting power of attorney, their scope, the point at which each can be used, and the age and bankruptcy conditions for donors and attorneys were checked against GOV.UK guidance on lasting powers of attorney.

The £92 registration fee, the availability of a reduction or exemption, and the eight to ten week registration period where there are no mistakes were checked against GOV.UK guidance on making a lasting power of attorney.

The duties owed by an attorney, including the presumption of capacity and the best interests requirement, were checked against GOV.UK guidance on making decisions for someone else and the Mental Capacity Act code of practice.

The role of the Office of the Public Guardian was checked against its own page on GOV.UK.

The separate positions in Scotland and Northern Ireland were checked against mygov.scot and nidirect.

No lawyers, law firms, judgments or individual legal cases were quoted or discussed.

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