A will can look perfectly clear on paper and still cause serious difficulty after someone dies. Questions about what makes a will invalid often arise when a family is already grieving, particularly where the will leaves an unexpected gift, excludes a relative, or was signed during a period of illness. Understanding the rules can help you make a will with confidence and recognise when a concern needs careful legal attention.
This article explains the main grounds on which a will may be challenged in England and Wales. Every situation turns on its facts, and an invalidity concern does not automatically mean that a challenge will succeed. However, acting early and preserving relevant documents can make a real difference.
What makes a will invalid in England and Wales?
For a will to be legally valid, it must meet formal signing requirements and reflect the genuine, informed wishes of the person making it. That person must generally have the mental capacity to make a will, understand what they are signing, and act freely rather than under pressure from somebody else.
A will may be invalid if it was not executed correctly, if the person lacked testamentary capacity, if they did not know or approve its contents, or if it resulted from fraud, forgery or undue influence. A will can also be revoked by a later valid will, by destruction in certain circumstances, or by marriage unless the will was made in contemplation of that marriage.
It is worth separating an invalid will from a will that feels unfair. A parent is usually free to leave their estate as they choose. Disappointment alone does not invalidate a will, although some people may have separate rights to make a claim for reasonable financial provision from an estate.
Signing and witnessing errors
The formalities for signing a will are strict. Most wills must be in writing and signed by the person making the will, or by someone else in their presence and at their direction. The person must intend their signature to give effect to the will.
The signature must be made or acknowledged in the presence of two witnesses who are present at the same time. Each witness must then sign the will in the presence of the person making it. A witness does not need to read the will or know its contents, but the required signing process must be followed.
Small procedural mistakes can have significant consequences. For example, if witnesses signed at different times without both being present when the signature was made or acknowledged, the will may not meet the legal requirements. Problems can also arise where it is unclear whether the deceased intended a mark, initial or signature to finalise the document.
A witness can usually witness a will even if they are related to the person making it. However, a witness should not be a beneficiary, nor should they be the spouse or civil partner of a beneficiary. In that situation, the will itself is not necessarily invalid, but the gift to that witness or their spouse or civil partner may fail. This can create a result that nobody intended.
Changes made after signing
Handwritten amendments, crossed-out clauses and added pages are common sources of dispute. An alteration made after the will was signed may be ineffective unless it was properly executed in the same way as the will itself, or the alteration was already present when the will was signed.
Where a document contains unexplained changes, the Probate Registry may require evidence about when and how they were made. Keeping a clear, signed final version of a will is far safer than relying on informal amendments.
Lack of mental capacity
A person making a will must have testamentary capacity. In plain terms, they need to understand that they are making a will, have a broad understanding of what they own, appreciate who may reasonably expect to benefit, and be able to make a decision free from a mental disorder that affects it.
Capacity is not judged solely by age, diagnosis or whether someone has needed support with other decisions. A person living with dementia, for example, may still have capacity to make a will at a particular time. Equally, someone who appears physically well may lack the necessary understanding because of illness, medication, confusion or another condition.
Capacity concerns are more likely to be raised where a will was made shortly before death, during a hospital admission, after a diagnosis affecting cognition, or where it makes a dramatic change to earlier wishes. Medical records, the evidence of witnesses and the file notes of the professional who prepared the will may all become relevant.
When there is any realistic doubt about capacity, a solicitor may recommend a contemporaneous medical assessment. This can help confirm the person’s understanding at the time and provide valuable evidence if the will is questioned later.
Not knowing or approving the will’s contents
Even where a will has been correctly signed and the person had capacity, it may be challenged if they did not know and approve its contents. This issue can arise when somebody is unable to read the document, has poor eyesight, does not understand English well, or relied heavily on another person to explain the will.
The concern is particularly serious where the person who helped prepare the will, arranged the signing or gave instructions also receives a substantial benefit under it. That does not automatically make the will invalid. It does, however, mean clear evidence may be needed to show that the person understood what the will said and wanted its terms.
Good will-making practice includes taking instructions directly from the person making the will where possible, explaining the document in accessible language, and recording the reasons for important decisions. These steps protect the person’s wishes as well as the people they intend to benefit.
Undue influence, fraud and forgery
Undue influence means more than persuasion, family disagreement or a relative expressing a strong opinion. People are entitled to encourage a loved one to make a will or discuss difficult family circumstances. The legal concern is whether pressure became so serious that the person was no longer making their own free decision.
Examples may include isolation from family or friends, threats to withdraw care, repeated intimidation, or controlling access to finances and legal advice. These cases can be difficult to prove because the pressure often happens privately. Evidence may come from messages, care records, medical notes, witness accounts and the circumstances surrounding the will.
A will can also be invalid if it was forged, if the signature was falsified, or if the person was deliberately misled about what they were signing. Allegations of fraud and forgery are serious. They should be handled carefully, with the original will and any relevant documents kept safe while legal advice is obtained.
Later wills, marriage and revocation
A valid later will usually revokes an earlier will if it includes a revocation clause or is inconsistent with the earlier document. This is why keeping several unsigned drafts or old originals without clear records can lead to uncertainty after death.
Marriage generally revokes an existing will in England and Wales, unless the will was expressly made in contemplation of that specific marriage. Divorce does not usually invalidate the whole will, but it can affect gifts and appointments made in favour of a former spouse or civil partner. The position can be more complicated where there are replacement provisions or jointly owned assets.
A will may also be revoked if the person deliberately destroys it, or directs another person to destroy it in their presence, with the intention of revoking it. A missing original will can therefore raise difficult questions. If the last known original cannot be found after death, there may be a presumption that it was destroyed deliberately, though that presumption can sometimes be challenged with evidence.
When a will dispute may need urgent attention
If you believe a will may be invalid, avoid altering the document, removing pages or relying on copies without checking their status. Keep the original safe, make a note of what you know about its preparation and signing, and preserve relevant communications. Time limits can apply to some estate-related claims, and estate assets may need to be protected while a dispute is considered.
Equally, if you are making or updating your own will, do not assume that a downloaded form or informal arrangement will suit a complex family position. Blended families, vulnerable beneficiaries, business interests, overseas assets and recent changes in health can all require greater care.
A professionally prepared will cannot prevent every disagreement, but clear instructions, proper witnessing and careful records can reduce uncertainty for the people you leave behind. If you are concerned about a will’s validity or want reassurance that your own wishes have been properly recorded, a conversation with a wills and probate solicitor can provide calm, practical guidance at a time when clarity matters most.
