Can a Will Be Challenged? The Legal Grounds for Contesting — And How to Make Yours Bulletproof

Will Disputes Are Rising — And Most Could Have Been Prevented

The number of contested Will cases in England and Wales has risen by more than 50 per cent over the past decade. The reasons are straightforward: families are more complex than ever, property values have risen dramatically, and the gap between what people expect to inherit and what they actually receive has never been wider.

Understanding the grounds on which a Will can be challenged — and the steps you can take to make yours resilient — is one of the most valuable things you can do to protect your family from expensive, emotionally devastating litigation after your death.

Ground 1: Lack of Testamentary Capacity

To make a valid Will, you must have testamentary capacity — the legal term for the mental ability to understand what you are doing. The test comes from the 1870 case of Banks v Goodfellow and requires that the person making the Will:

• Understands they are making a Will and its effect
• Understands the extent of their estate (in broad terms, not precise values)
• Can comprehend the claims of people who might expect to benefit
• Is not suffering from any disorder of the mind that influences their decisions

This is the most common ground for challenge, particularly when the Will-maker was elderly or had been diagnosed with dementia. However, a diagnosis of dementia does not automatically mean someone lacks capacity — capacity can fluctuate, and many people with early-stage dementia retain the ability to make valid decisions.

How to protect against this: If there is any question about capacity, have a medical professional assess the Will-maker at the time the Will is signed. A contemporaneous capacity assessment — ideally by the person’s GP or a specialist — creates strong evidence that capacity existed at the relevant moment.

Ground 2: Undue Influence

A Will can be set aside if someone pressured or coerced the Will-maker into making provisions they would not otherwise have made. Unlike some other legal areas, undue influence in Will cases must be proven by the person alleging it — there is no presumption.

Common scenarios include a child who has become the primary carer and uses that position to isolate the parent from other family members, or a new partner who encourages the Will-maker to disinherit children from a previous relationship.

How to protect against this: The Will-maker should meet with their solicitor alone, without the person who stands to benefit most. The solicitor’s attendance note should record that they were satisfied the instructions were given freely. If a significant change is being made — such as disinheriting a child — the solicitor should document the reasons in detail.

Ground 3: Lack of Knowledge and Approval

Even if the Will-maker had capacity, a challenge can succeed if they did not truly know and approve the contents of the Will. This arises most often when:

• The Will was prepared by someone who benefits from it
• The Will-maker was blind, illiterate, or did not speak the language in which the Will was written
• The Will contains provisions that are surprising or inconsistent with the Will-maker’s known wishes

How to protect against this: Have an independent solicitor prepare the Will. If the Will-maker has any communication difficulties, ensure the Will is read aloud and explained, and record that this was done.

Ground 4: Improper Execution

A Will must comply with section 9 of the Wills Act 1837:

• It must be in writing
• It must be signed by the Will-maker (or by someone else in their presence and at their direction)
• The signature must be made or acknowledged in the presence of two witnesses
• Both witnesses must sign the Will in the presence of the Will-maker

If any of these formalities are missing, the Will is invalid. The most common errors are witnesses who were not both present at the same time, a witness who is also a beneficiary (which does not invalidate the Will but voids their gift), and Wills signed but not witnessed at all.

How to protect against this: Use a professional Will-writer or solicitor who follows proper execution procedures. If signing at home, ensure both witnesses are present throughout and are not beneficiaries or married to beneficiaries.

Ground 5: The Inheritance (Provision for Family and Dependants) Act 1975

Even a perfectly valid Will can be challenged under this Act if it fails to make “reasonable financial provision” for certain categories of people:

• The spouse or civil partner of the deceased
• A former spouse or civil partner who has not remarried
• A child of the deceased (of any age)
• A person treated as a child of the family
• A person who was financially maintained by the deceased
• A cohabitant who lived with the deceased for at least two years before death

The court considers the applicant’s financial needs, the size of the estate, any obligations the deceased had to the applicant, any disability, and any other relevant matter. Spouses are assessed on a higher standard — whether the provision is reasonable in all circumstances — while other applicants are assessed on whether they received enough for their maintenance.

How to protect against this: If you are deliberately excluding someone who falls into one of these categories, explain your reasons in a letter of wishes (a separate document, not part of the Will itself). Consider whether a modest provision might prevent a costly claim. Take legal advice on structuring your estate to reduce vulnerability to such claims.

Ground 6: Fraud and Forgery

Though rare, Wills can be challenged on the basis that they are forged or that the Will-maker was deceived into signing. This includes cases where someone misrepresents the contents of the document or fabricates a Will entirely.

The Cost of Will Disputes

Contested probate cases are among the most expensive areas of litigation. Legal costs of £50,000 to £100,000 per side are common, and cases that reach trial can cost significantly more. These costs are often paid from the estate, meaning every beneficiary loses — even the one who wins.

The emotional cost is equally severe. Will disputes frequently destroy family relationships permanently. Siblings who contest a parent’s Will rarely speak again.

Seven Steps to Make Your Will Bulletproof

1. Use an independent, qualified solicitor or Will-writer
2. If capacity is in any doubt, get a contemporaneous medical assessment
3. Meet your solicitor alone — without the person who benefits most
4. Document your reasons if you are excluding someone who might expect to inherit
5. Review your Will every three to five years and after any major life event
6. Consider a letter of wishes to explain your decisions (kept separate from the Will)
7. Keep the original Will in safe storage and tell your executors where it is

The best way to prevent a Will dispute is to make a Will that is clear, properly executed, and difficult to challenge. The few hundred pounds it costs to do this properly is a fraction of what your family would spend defending it in court.