What Makes a Will Invalid in the UK? 7 Common Mistakes

Emma, a 42-year-old mother of three, thought she'd done everything right. She carefully wrote out her will, signed it at the kitchen table, and asked her sister and brother-in-law—who were visiting that afternoon—to witness her signature. Three years later, when Emma died unexpectedly from a heart attack, her £340,000 estate descended into chaos.

Her sister had inherited £50,000 under the will, and because she'd acted as a witness, that gift was automatically void under Section 15 of the Wills Act 1837. Worse, the brother-in-law had stepped into the hallway to answer a phone call while Emma's sister was signing, meaning the witnesses weren't present simultaneously. The entire will was declared invalid.

This isn't a rare tragedy. Inheritance disputes in the High Court increased significantly between 2016-2019, with poorly drafted DIY wills blamed for probate problems affecting up to 38,000 UK families annually. Understanding what makes a will invalid isn't just academic—it's about protecting your family from devastating legal battles at the worst possible time.

This article reveals the seven critical reasons UK wills become invalid, the legal requirements under the Wills Act 1837, and exactly how to ensure your will stands up to scrutiny.

Understanding UK Will Validity: The Wills Act 1837 Framework

The Wills Act 1837 has governed UK wills for nearly 200 years. Section 9 sets out the critical validity requirements that every will must meet.

Under Section 9, a will is valid only if it meets four fundamental requirements: it must be in writing, signed by the testator or someone in their presence acting under their direction, made with the testator's clear intention to give effect to the will, signed or acknowledged in the presence of two witnesses present simultaneously, and witnessed by two people who sign in the testator's presence.

When a will is declared "invalid," it has no legal effect whatsoever. The estate is distributed either under a previous valid will or, if none exists, under intestacy rules—which rarely reflect what the deceased person actually wanted.

As many as 10,000 people in England and Wales dispute a will each year, but in 2021-22, only 195 disputes resulted in court appearances. Most are settled before court or abandoned entirely. However, when wills are successfully challenged, the consequences are devastating.

This article covers the rules for England and Wales. Scotland has different requirements, including only needing one witness rather than two. Remote witnessing via video was permitted during COVID but expired in January 2024—only in-person witnessing is now valid.

While the legal framework seems straightforward, seven critical mistakes can invalidate an otherwise well-intentioned will. Here's what you absolutely must avoid.

Reason 1: Improper Witnessing (The Most Common Mistake)

Improper witnessing is the single most common reason wills are declared invalid. The requirements seem simple, but the details trip up thousands of people every year.

The simultaneous presence rule is absolute: the testator and both witnesses must be physically present together when the will is signed. The specific sequence matters: first, the testator signs in the presence of both witnesses. Then the first witness signs in the presence of the testator and second witness. Finally, the second witness signs in the presence of the testator and first witness.

Everyone must watch everyone else sign. If one witness steps out to answer a phone call, goes to another room, or arrives late after the testator has already signed, the entire will fails.

Michael, 67, had both witnesses sign his will via Zoom in February 2024, not realizing remote witnessing expired on January 1, 2024. When he died six months later, his £280,000 estate was distributed under intestacy rules rather than his carefully planned will. His unmarried partner of 15 years received nothing—exactly what he'd tried to prevent.

Witnesses must be 18 years or older, not blind, and mentally capable of understanding what they're witnessing. They don't need to read the will's contents, but they must understand they're witnessing a legal signature.

Common mistakes include witnesses signing in different rooms, one witness arriving late and signing after the testator has left, using Zoom or Skype witnessing after COVID provisions expired, and using a witness under 18 years old.

The solution is straightforward but must be followed precisely: all three people—testator plus two witnesses—must be in the same room simultaneously. Everyone watches everyone else sign. No one leaves until all three signatures are complete.

Learn who can witness a will in the UK to ensure you choose appropriate witnesses.

But even perfectly witnessed wills can fail if the witness themselves has a conflict of interest.

Reason 2: Beneficiary or Their Spouse Acts as Witness (Section 15 Complication)

Under Section 15 of the Wills Act 1837, if a beneficiary or their spouse or civil partner witnesses the will, the will remains valid but the gift to that beneficiary becomes void.

This is different from improper witnessing, which invalidates the entire will. Here, the will stands but the beneficiary loses their inheritance completely. Their gift is redistributed under the residuary clause or intestacy rules.

James left his daughter £80,000 in his will and asked her to witness it alongside her neighbour. The will was perfectly executed—both witnesses present simultaneously, all formalities followed correctly. When James died, his daughter discovered she would inherit nothing. Her £80,000 share was redistributed among his other children.

There's an important exception: if the will has three witnesses and two are independent, the gift is saved. But most wills only have two witnesses, so this exception rarely helps.

Section 15 only applies at the time of signing. If a witness marries a beneficiary after the will is executed, the gift is not void. But if a beneficiary's spouse acts as witness—even if the beneficiary themselves doesn't sign—the beneficiary's gift still fails.

The Law Commission is considering extending these rules to cohabiting couples, who currently aren't covered. Under current law, a cohabiting partner can witness a will leaving them money, and the gift remains valid—but this is widely considered a loophole that needs closing.

Who Can and Cannot Witness Your Will:

Can Witness	Cannot Witness (Gift Becomes Void)
Friends	Beneficiaries
Neighbours	Spouses or civil partners of beneficiaries
Colleagues	Anyone who inherits under the will
Professional advisors (who don't benefit)	Executors who also benefit

Many people think asking a family member to witness is fine. It is—if that family member doesn't benefit from the will. Your son can witness your will if he's not a beneficiary, but if he inherits anything, his gift becomes void the moment he signs as witness.

Follow our step-by-step guide to signing your will correctly to avoid these witnessing pitfalls.

Beyond witnessing issues, the mental state of the person making the will can be grounds for invalidation.

Reason 3: Lack of Testamentary Capacity

Testamentary capacity means having the mental ability to make a valid will. The legal standard comes from Banks v Goodfellow (1870), a case that remains the cornerstone of UK law more than 150 years later.

The testator must meet four requirements: understand the nature and effect of making a will, know the extent of their property and assets, comprehend who has claims on their estate (family members and dependents), and not have delusions or mental disorders influencing their decisions.

Capacity challenges are increasing due to the UK's ageing population and rising rates of dementia and Alzheimer's. However, people with dementia can make valid wills if they have testamentary capacity at the time of signing. Capacity is decision-specific and time-specific—someone might lack capacity one day but have a lucid moment the next.

Patricia, 78, made a will three months after her dementia diagnosis. She left her entire estate to one son, excluding her other two children. The excluded children challenged the will on capacity grounds. Medical records showed Patricia understood her assets (her £220,000 home and £45,000 in savings), recognised all three children's claims on her estate, and clearly explained why she chose to leave everything to the son who'd cared for her during her illness. The will was upheld.

Medical capacity assessments can provide crucial evidence. A GP or specialist can provide written confirmation that the testator understood the nature of making a will at the specific time they signed it.

Red flags that often trigger capacity challenges include a will made shortly after dementia or Alzheimer's diagnosis, a will significantly different from previous wills without clear explanation, the testator being on heavy medication affecting cognitive function, and the testator under the influence of alcohol or drugs when signing.

Protection strategies include getting a medical capacity assessment for vulnerable testators, including detailed notes documenting the testator's awareness and understanding, considering video recording the will signing (not required but helpful evidence), and asking capacity self-assessment questions during the will-making process.

Important note: If you have concerns about your mental capacity or a loved one's capacity to make a will, please consult a medical professional and solicitor who can provide a formal capacity assessment. This article provides general information only.

While some people lack capacity to make decisions, others make those decisions under pressure they cannot resist.

Reason 4: Undue Influence and Coercion

Undue influence means coercion that overpowers the testator's free will, leaving them no real choice. It's different from persuasion—family members can discuss wishes and encourage certain decisions, but they cannot threaten, coerce, or manipulate.

The burden of proof is high. The challenger must prove coercion actually occurred, not just that circumstances look suspicious. Successful undue influence claims are rare, with very few succeeding even when circumstances raise red flags.

Vulnerable groups include elderly and isolated individuals, those dependent on carers, people with cognitive decline, and anyone in a relationship with a power imbalance.

Eleanor, 82, lived with her nephew who controlled her finances and isolated her from other family. She changed her will to leave everything to the nephew, excluding her three daughters. The will was successfully challenged when the daughters proved the nephew prevented them from visiting, controlled Eleanor's phone access, and Eleanor feared losing her home if she didn't comply. Bank records showed the nephew had transferred money from Eleanor's accounts without her knowledge.

Red flags for undue influence include a testator suddenly changing a long-standing will without explanation, the new beneficiary being a caregiver or person in a position of power, the testator isolated from other family members, the beneficiary arranging the will signing and selecting witnesses, and a pattern of financial control or coercive behaviour.

The Law Commission proposed 2025 reforms to allow courts to infer undue influence from suspicious circumstances without requiring direct proof of coercion. This responds to criticism that current law fails to protect vulnerable testators because coercion almost never happens in public, and by the time anyone can challenge, the testator is dead.

Under current law, the challenger must prove undue influence was more probable than any other explanation. If another possibility is equally likely, undue influence will not be established.

Beyond psychological coercion, outright fraud can invalidate a will entirely.

Reason 5: Fraud, Forgery, or Lack of Knowledge and Approval

Three related grounds can invalidate a will: fraud, forgery, and lack of knowledge and approval. Each has different legal elements but similar devastating consequences.

Fraud occurs when the will is procured through fraudulent misrepresentation. For example, a beneficiary tells the testator "your daughter is dead" to exclude her from the will, when the daughter is actually alive. The testator's decision is based on false information deliberately provided.

Forgery means the will or signature was forged entirely. Success rates are under 10% because forgery is extremely difficult to prove, requiring handwriting experts and forensic document analysis. But if proven, the will is completely void.

Lack of knowledge and approval means the testator signed without understanding the will's contents. This is different from lack of capacity—the person has the mental ability to make a will, but they don't know what's actually in the document they're signing.

Arthur, 89, was asked to sign "some paperwork" by his carer. He signed without reading it, not knowing it was a will leaving everything to the carer and excluding his grandchildren. The will was declared invalid for lack of knowledge and approval despite Arthur having testamentary capacity. He had the mental ability to make a will, but he didn't know he was doing so.

Common situations involving knowledge and approval issues include blind or illiterate testators, language barriers where the will isn't in the testator's first language, and the will being read incorrectly or incompletely to the testator.

Courts presume knowledge and approval if the will was properly executed and the testator had capacity. The challenger must prove otherwise, which requires strong evidence. Fraud and forgery claims succeed in fewer than 10% of cases due to this high burden of proof.

Protection strategies include ensuring the testator reads the will before signing or has it read to them accurately, documenting that the testator understands the contents, and for non-English speakers, providing accurate translation or using a bilingual witness who can confirm understanding.

Even a perfectly executed will with full capacity and knowledge can be automatically invalidated by a single life event.

Reason 6: Marriage or Civil Partnership Automatically Revokes Previous Wills

Under Section 18 of the Wills Act 1837, marriage or civil partnership automatically revokes any previous will. This rule applies throughout England, Wales, and Northern Ireland (Scotland has different rules).

The exception is narrow: the will survives if it was made "in contemplation of marriage" to a specific person and the testator intended the will not to be revoked by that marriage. This intention must be explicitly stated in the will itself.

David made a comprehensive will in 2018, carefully planning who would inherit his £450,000 estate. In 2023, he married his long-term partner but forgot to update his will. When he died in 2024, his 2018 will was void. His estate was distributed under intestacy rules—his adult children from his previous relationship inherited more than he intended, and his spouse received less than he'd planned to leave her.

Divorce does not automatically revoke a will. It only removes the ex-spouse as beneficiary and executor—they're treated as if they died before the testator. The rest of the will remains valid.

Importantly, the conversion of a civil partnership to marriage does not revoke a will, thanks to the Marriage (Same Sex Couples) Act 2013.

The automatic revocation rule exists to protect new spouses who might otherwise be disinherited. The assumption is that marriage fundamentally changes the testator's intentions about inheritance. However, the Law Commission is considering reform due to concerns about "predatory marriages" involving vulnerable elderly people.

If you're engaged, you can include an "in contemplation of marriage to [full name of fiancé]" clause in your will. This prevents automatic revocation when you marry that specific person.

The safest approach is always to review and update your will after marriage or civil partnership. Don't assume your existing will still works—it probably doesn't.

Beyond automatic revocation, physical changes to your will can also create validity problems.

Reason 7: Invalid Alterations or Amendments

Under Section 21 of the Wills Act 1837, any alteration made after the will is executed must be signed or initialed by the testator in the margin or near the alteration and witnessed by two witnesses who also sign or initial.

Otherwise, the alteration has no legal effect. Courts ignore it entirely—the original wording stands, if readable.

Robert crossed out "£50,000" next to his daughter's gift and wrote "£75,000" in its place. He initialed the change but didn't have witnesses sign. When he died, the alteration was invalid. His daughter received the original £50,000, not the increased amount Robert clearly intended.

If the original wording is unreadable after the alteration—for example, if it's been scribbled out or covered with correction fluid—that provision may fail entirely. This can leave gaps in your estate plan that must be filled by residuary clauses or intestacy rules.

A better approach is to execute a formal codicil (an amendment document that requires the same witnessing formalities as a will) or make an entirely new will. Both require two witnesses present simultaneously, just like the original will.

Common mistakes include crossing out beneficiaries without witnessing, adding handwritten notes in margins, changing amounts without proper execution, and using correction fluid or tape to cover mistakes (which makes courts suspicious about fraud).

Courts presume alterations were made after execution unless proven otherwise. If an alteration appears to be made before execution—during the drafting process—it's valid without separate witnessing. But the burden of proof lies with the person claiming the alteration was made before execution.

The proper amendment process:

Make changes on your computer or paper
Re-execute the entire will with two witnesses present simultaneously
Or execute a formal codicil with two witnesses
Never make handwritten changes without proper witnessing

For comprehensive guidance on all will requirements, read how to make a will in the UK.

Understanding these seven reasons is critical, but what actually happens when a will is declared invalid?

What Happens When a Will Is Declared Invalid?

When a will is declared invalid, the court follows a clear hierarchy to determine who inherits.

First, if a previous valid will exists, that will governs the estate distribution. Courts look for the most recent valid will, which might be years or even decades old.

Second, if no previous valid will exists, intestacy rules determine who inherits. These rules can produce dramatically different outcomes than the testator intended.

Under UK intestacy rules, unmarried partners inherit nothing—even after decades together. Married spouses receive only the first £322,000 plus 50% of the remainder if children exist. The entire estate may go to distant relatives rather than intended beneficiaries.

Jennifer's will was invalid due to a witnessing error. Her previous will, made 15 years earlier before her second marriage, left everything to her first husband's children. Her second husband and their two children received nothing—the complete opposite of her clear intentions.

Contesting will validity takes time and money. Disputes typically last 12 to 24 months and cost £10,000 to £50,000 or more in legal fees. Emotional costs are equally severe—family relationships are often permanently damaged by will disputes.

Sometimes only part of a will is invalid. For example, one gift might be void due to a beneficiary witness, but the rest of the will stands. Courts try to uphold as much as legally possible using the doctrine of "partial intestacy."

For more information about intestacy consequences, learn what happens if you die without a will in the UK.

Given these severe consequences, how can you ensure your will is legally bulletproof?

How to Ensure Your Will Is Valid and Challenge-Proof

Creating a valid will requires careful attention to legal requirements and practical safeguards. Follow these steps to protect your estate from invalidity challenges.

Step 1: Meet Core Legal Requirements

Your will must be in writing (typed or handwritten—both are valid if properly witnessed). You must sign it in the presence of two independent witnesses who watch you sign. Both witnesses must be present simultaneously throughout the signing process. Witnesses must be 18 years or older, not blind, and mentally capable. Witnesses cannot benefit from the will or be married to beneficiaries.

Step 2: Choose Proper Witnesses

Best options are neighbours, friends, or colleagues with no interest in your estate. Avoid family members who might benefit and executors who also inherit. Never ask beneficiaries or their spouses to witness—their gifts will become void.

When you're ready to sign, use WUHLD's free Witness Guide PDF for step-by-step instructions that ensure compliance with all legal requirements.

Step 3: Document Capacity

If you have any health conditions affecting cognition, get a medical capacity assessment from your GP or a specialist. Make your will during a period of clear mental health. Keep detailed notes about your reasoning and wishes. This documentation becomes crucial evidence if your capacity is later challenged.

Step 4: Make Your Will in a Conducive Environment

Choose a private location without interruptions. Don't make decisions while under the influence of alcohol or medication. Allow adequate time—never sign under pressure or time constraints. Ensure you fully understand the contents before signing. Read the entire will carefully, or have someone read it to you if you have vision problems.

Step 5: Store Your Will Safely and Communicate

Tell your executors where your will is stored. Keep it in a fireproof location or register it with the National Will Register. Review and update your will every three to five years or after major life events (marriage, divorce, birth, death, significant asset changes).

Step 6: Use Professional Guidance When Needed

Complex estates may need a solicitor. These include multiple properties, business assets, overseas assets, trusts, expected family disputes, or situations where capacity might be questioned.

WUHLD is suitable for straightforward UK estates: one property, standard assets, clear beneficiaries, and no complex tax planning. Our guided process includes validity checks at every step.

How WUHLD Prevents Invalidity:

Our platform includes automated compliance with Wills Act 1837 requirements, clear witnessing instructions with a free Witness Guide PDF, built-in checks for beneficiary witnesses, capacity self-assessment questions, plain English guidance that eliminates confusion, and the ability to preview your entire will free before paying—see exactly what you're signing.

Cost Comparison:

Method	Cost	Validity Protection	Time Required
DIY (paper forms/online templates)	£10-£30	Low (38,000 families face problems annually)	2-4 hours + research
WUHLD	£49.99 one-time	High (guided compliance + witnessing instructions)	15 minutes
Solicitor	£650-£2,000+	Highest (professional oversight)	3-6 weeks + multiple appointments

When to Use Each:

Use WUHLD for straightforward estates, standard wishes, and when you need a quick, legally valid will. Use a solicitor for complex assets, business ownership, trusts, when family disputes are expected, or if capacity might be contested.

Your will is one of the most important documents you'll ever create. Getting it right protects your family from devastating legal battles when they're already grieving.

Frequently Asked Questions

Q: What happens if a will is found to be invalid in the UK?

A: If a will is declared invalid, the court looks for a previous valid will. If one exists, it governs the estate distribution. If no previous valid will exists, the estate is distributed under intestacy rules, which may not reflect the deceased person's intentions at all.

Q: Can a handwritten will be valid in the UK?

A: Yes, handwritten wills are valid in the UK if they meet the same requirements as typed wills under Section 9 of the Wills Act 1837. The will must be signed by the testator in the presence of two independent witnesses aged 18 or over, who must also sign in the testator's presence. The format doesn't matter—what matters is proper execution and witnessing.

Q: Does marriage invalidate a will in the UK?

A: Yes, marriage or civil partnership automatically revokes any previous will in England, Wales, and Northern Ireland under Section 18 of the Wills Act 1837. The only exception is if the will was made "in contemplation of marriage" to that specific person and explicitly states it should not be revoked by that marriage. Always review and update your will after getting married.

Q: Can a beneficiary witness a will in the UK?

A: A beneficiary can technically witness a will, but doing so has serious consequences. Under Section 15 of the Wills Act 1837, the will remains valid but the gift to that beneficiary becomes void. The same applies if the beneficiary's spouse or civil partner acts as witness. Always use independent witnesses who don't benefit from the will.

Q: How long does it take to contest a will in the UK?

A: Contesting a will typically takes 12 to 24 months and costs £10,000 to £50,000 or more in legal fees. Most disputes are settled out of court, but court proceedings add significant time and expense. The emotional toll on families can be even more devastating than the financial costs.

Q: What is testamentary capacity?

A: Testamentary capacity is the mental ability required to make a valid will. Under the Banks v Goodfellow test from 1870, the testator must understand the nature and effect of making a will, know the extent of their property, comprehend who has claims on their estate, and not have delusions influencing their decisions. People with dementia can make valid wills if they have capacity at the time of signing.

Protect Your Family From Will Invalidity

Creating a legally valid will protects your family from years of court battles and ensures your final wishes are honoured. Here's what you must remember:

Ensure your will meets all Wills Act 1837 requirements: written, signed by you, properly witnessed by two independent witnesses aged 18 or over who are present simultaneously
Never use beneficiaries or their spouses as witnesses—their gifts become void under Section 15, even though the will itself remains valid
Document your testamentary capacity if you have any health conditions, and never make decisions under pressure, coercion, or undue influence
Remember that marriage automatically revokes previous wills unless made in contemplation of that specific marriage with explicit language preserving the will
Never make handwritten alterations without re-executing the entire will or creating a properly witnessed codicil—unmarked changes are invalid under Section 21

38,000 UK families face probate problems annually because of invalid or poorly drafted wills. These aren't just statistics—they're families torn apart by legal battles, estates depleted by court costs, and final wishes lost forever to intestacy rules. The difference between a valid will and an invalid one often comes down to simple technical requirements that take minutes to get right.

WUHLD makes it impossible to miss these critical requirements. Our guided online process includes automatic Wills Act 1837 compliance checks, clear witnessing instructions with a free Witness Guide PDF, and plain English guidance that eliminates confusion. You can preview your complete will free before paying—no credit card required.

For £49.99 (not £650+ for a solicitor), you get:

Your complete, legally binding will
A 12-page Testator Guide explaining how to execute your will properly
A Witness Guide to give to your witnesses
A Complete Asset Inventory document

Create your legally valid will in 15 minutes and protect your family's future today.

Preview Your Will Free – No Payment Required

Legal Disclaimer: This article provides general information about UK will validity requirements under the Wills Act 1837 and does not constitute legal advice. For advice specific to your individual situation, please consult a qualified solicitor. WUHLD's online will service is suitable for straightforward UK estates; complex situations involving business assets, overseas property, trusts, or expected disputes may require professional legal advice.

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