There are two types of power of attorney.
Ordinary power of attorney
This is a legal document that allows someone (it can be more than one person) you have chosen to act for you in financial matters only, making decisions on your behalf.
This can be in regard to specific matters or be general to cover all of your finances. An ordinary power of attorney can only be given if you have the mental capacity to make this decision and should you become without capacity, for example, due to a major illness, it becomes invalid.
An ordinary power of attorney can be useful if you are temporarily unable to manage your financial affairs, for example, if you are out of the country or just need the help of someone you trust to manage your affairs.
Lasting power of attorney
This is a legal document that allows someone (it can be more than one person) you have chosen to act for you in property and financial affairs and personal welfare decisions when you no longer have the mental capacity to do this yourself.
It is different from an ordinary power of attorney in that whilst you must have the mental capacity to make the decision to grant this to someone, and not to have been placed under pressure to do so, the power to act on your behalf continues after you lose capacity.
A lasting power of attorney must also be registered with the Office of the Public Guardian (OPG) to be valid and the OPG will oversee the person or persons appointed as "deputy" to act.
The OPG is the administrative arm of the Court of Protection that is ultimately responsible for decisions relating to people who lack mental capacity. The OPG have the relevant documents you require to apply for a lasting power of attorney.
A solicitor or legal advice agency can help you obtain and complete the required forms. The OPG website gives details and advice.