Who Cannot Witness an LPA?

Written by Anthony Dalton · Reviewed by James Tyrrell · Last reviewed 16 March 2026

Getting the witnessing wrong on an LPA is one of the most common — and most frustrating — mistakes people make. The Office of the Public Guardian (OPG) rejects hundreds of applications each year for witnessing errors, and there is no way to fix the mistake on the existing document. You have to start over, pay the £92 registration fee again, and get all the signatures redone. The Mental Capacity Act 2005 and the LPA regulations set out clear rules about who is prohibited from witnessing. This guide explains exactly who cannot witness an LPA and why.

Attorneys Cannot Witness the Donor's Signature

The most important restriction — and the one most commonly breached — is that an attorney named in the LPA cannot witness the donor's signature. This applies to every attorney appointed under the LPA, whether they are an original attorney or a replacement attorney. The rule exists to protect the donor from potential undue influence. If the person who stands to gain decision-making power is also the one confirming the donor signed freely, there is an obvious conflict of interest.

This restriction is absolute. Even if the attorney is also a close family member, a trusted friend, or the donor's spouse, they cannot witness the donor's signature under any circumstances. If an attorney does witness the donor's signature, the OPG will reject the entire LPA, and you will need to start the process again from scratch.

Anyone Under 18 Cannot Be a Witness

A witness for any part of an LPA must be aged 18 or over. A person under the age of 18 — regardless of how mature or responsible they may be — is not legally permitted to act as a witness. This rule applies to witnessing the donor's signature, the attorneys' signatures, and the replacement attorneys' signatures alike.

There are no exceptions to the age requirement. Even a 17-year-old who is days away from their 18th birthday cannot act as a witness. If the OPG discovers that a witness was under 18 at the time of signing, the LPA will be rejected.

The Donor Cannot Witness Their Own LPA

It may seem obvious, but the donor — the person creating the LPA — cannot act as a witness for any signature on their own document. The donor cannot witness an attorney's signature in a formal capacity on the witness line, though the donor's presence when an attorney signs is not itself a problem. The witness must be an independent third party who is watching the person sign and then adding their own name and address to confirm they saw the signature being made.

Note that while the donor is not listed in the witness box, the donor can be present when attorneys sign. The key distinction is between being present and formally acting as the named witness on the document.

Certificate Providers and Witnessing Attorney Signatures

The certificate provider has a unique position in the LPA process. They are the independent person who confirms that the donor understands the LPA and is not being pressured into making it. While the certificate provider can witness the donor's signature, they cannot witness the attorneys' signatures if they are also named as an attorney or replacement attorney in the document.

In practice, the certificate provider is usually a separate individual from all attorneys, so this restriction rarely causes issues. However, it is worth being aware of the rule to avoid any complications. For a full explanation of the certificate provider's role, see our guide on what a certificate provider is.

People Who Lack Mental Capacity

A witness must have the mental capacity to understand what they are doing — namely, that they are watching someone sign a legal document and confirming that they saw the signature being made. A person who lacks mental capacity cannot serve as a witness, even if they are over 18 and otherwise eligible.

In most cases, this is straightforward. The act of witnessing a signature is not complex, so the threshold for capacity is relatively low. However, if there is any doubt about whether a potential witness understands what they are being asked to do, it is best to choose someone else.

Summary of Who Cannot Witness Each Part

The restrictions differ depending on which part of the LPA is being witnessed. Here is a clear breakdown:

What Happens If the Wrong Person Witnesses Your LPA

If someone who is not permitted to act as a witness does so, the LPA will be invalid. When you submit the document to the OPG for registration, they will review the witness details and check for any breaches of the rules. If they find a problem, the LPA will be rejected. You will then need to complete an entirely new LPA document, have it signed and witnessed correctly, and pay the £92 registration fee again.

There is no way to correct a witnessing error on an existing LPA. You cannot simply cross out the invalid witness and replace them — the entire document must be redone. This is why it is so important to understand the rules before you begin the signing process.

For more on who can witness an LPA, read our companion guide on who can witness an LPA signature. You may also find it helpful to understand whether a family member can witness an LPA, which covers the practical considerations for choosing a family witness.

Key Questions on LPA Witnessing Restrictions

This guide was last reviewed and updated on 16 March 2026. Information is based on current legislation and OPG guidance for England and Wales.

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