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Capacity and the mind of the testator

This information applies only to England, Wales and Northern Ireland.


In order to make a valid will, the testator (a person making a will) must be 18 or over when they sign the will, unless they are a soldier or airman on actual military service or a sailor at sea. In that case, the testator is given a specific privilege to make a will at an age less than 18.

Further, in Northern Ireland, under the Wills and Administration Proceedings (NI) Order 1994, further categories of privilege are also extended to minors who can satisfy the qualifying criteria set out in the legislation and minors who are married or in a civil partnership.

Testamentary capacity

The testator must have the requisite mental capacity when they signed their will. This testamentary capacity has been defined as 'soundness of mind, memory and understanding'.

This requires a testator:

  • To understand the nature of the act of making a will
  • To know which persons they should consider as possible beneficiaries
  • To be able to understand the property of which they are disposing
  • Not to be suffering from any delusion or disorder of mind which influences the provisions of their will

If the testator lacked the requisite mental capacity at the time they signed their will, then generally the will is invalid.

There is a presumption that, unless the contrary is proved, the testator has capacity, so the burden of proving that the testator lacked testamentary capacity falls on the person who seeks to prove, after the testator's death, that the will is invalid.

If the will appears rational, then that helps towards establishing that the testator did have testamentary capacity.

Practical precautions

If there is any doubt as to whether the testator had the necessary testamentary capacity to make the will, it may be advisable to arrange for a medical practitioner to examine the testator at the time the will is to be signed to verify their mental capacity and to have that medical opinion recorded. It will also make practical sense to ask the examining practitioner to witness the will.

Intention to make a will

It is sometimes said that, in order to make a valid will, a testator must intend to make a will. This is not entirely accurate, although it is a convenient shorthand. In fact, a testator must have a 'testamentary intention', which means that the testator must intend the wishes they express to take effect only on their death, but need not be aware that they are making a will.

Undue influence and fraud

A will must not be made as a result of either the undue influence or the fraud of another person.

Undue influence means coercion; i.e. the testator is coerced into making a will (or part of a will) which they do not want to make. Generally, considerable pressure must be exerted before there is any chance of a finding of undue influence.

Fraud consists of deceiving the testator. For example, it would be fraud to tell a testator that a potential beneficiary had done or said something of which the testator would disapprove, when they had not.

Lack of knowledge and approval

Generally, a testator must know and approve the contents of their will at the time that they sign it.

A testator who has the necessary capacity and has signed their will is presumed to have the requisite knowledge and approval. However, there are circumstances where the presumption does not apply. This occurs in the case of a blind or illiterate person or a person who does not sign personally. The presumption of the testator's knowledge and approval does not apply if the testator is deaf and dumb, blind or illiterate or another person signs the will on their behalf (for example, because they have an injured hand).

Where there is doubt as to whether a testator has the requisite knowledge, the probate registrar will require evidence of the testator's actual knowledge and approval. In cases where the testator is blind, illiterate or does not sign personally, it is best that the will is read out and approved by the testator in front of the witnesses. At the end of the will (where provision is made for signature by the witnesses), a clause should be inserted confirming that the will was read over to the testator and the testator understood and approved its contents. This clause is known as the attestation clause. Without such an attestation clause, the probate registrar will require affidavit evidence of the testator's knowledge and approval from a witness or someone else who was present at the signing of the will.

Where there are suspicious circumstances surrounding the drafting or signing of the will, it will be up to the person seeking to rely on the will to remove that suspicion. This may result, for example, where a solicitor is drafting the will under which they will inherit as a beneficiary.

It may also be that all or part of the will was included by mistake. Any words included without the knowledge and approval of the testator cannot be relied upon. Generally, the court will not intervene over words which were badly selected and used by a testator who was merely mistaken about their legal effect.

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