Can Someone With Dementia Sign a Will?

Yes, sometimes — but only if they have sufficient mental capacity at the time of signing. A dementia diagnosis doesn't automatically prevent someone from making a valid will.

This is a nuanced area that catches many families off guard. The key isn't whether someone has dementia, but whether they have "testamentary capacity" — the legal ability to make a will — at the specific moment they sign it.

The Legal Test for Capacity

To make a valid will, a person must understand:

1. What making a will means — they're deciding who gets their property when they die
2. What they own — a general idea of their assets and their value
3. Who might expect to inherit — family members and others who have claims on their estate
4. How these factors relate — they can weigh up these considerations

This test comes from an 1870 case called Banks v Goodfellow and is still used today.

How Dementia Affects Capacity

Capacity Fluctuates

Many people with early or moderate dementia have "lucid intervals" — periods when they're clearer and more capable. A will signed during a lucid interval can be perfectly valid.

It's Time-Specific

Capacity is assessed at the moment of signing, not generally. Someone might lack capacity on Tuesday but have it on Thursday. What matters is their state when they actually sign the will.

The Bar Isn't As High As You Think

You don't need perfect memory or complete clarity. You need to understand the basics of what you're doing. Many people with mild dementia can meet this threshold.

Warning Signs Capacity May Be Insufficient

• Can't remember what assets they have, even with prompting
• Don't recognise close family members
• Can't explain why they want to leave things as they do
• Decisions contradict long-held wishes without explanation
• Easily confused about basic facts
• Can't retain information for the length of the meeting

How to Make a Will With Dementia Safely

Step 1: Get a Medical Assessment

Before the will is prepared, get a doctor (ideally their GP or a specialist) to assess capacity. This should:

• Be done close to the will-signing date
• Specifically assess testamentary capacity (not just general capacity)
• Be documented in writing
• Include the doctor's opinion and reasoning

This is called the "Golden Rule" — always get medical evidence when there's any doubt about capacity.

Step 2: Use an Experienced Solicitor

A solicitor experienced in capacity issues will:

• Know what questions to ask
• Document the process thoroughly
• Recognise warning signs
• Potentially video the signing as evidence
• Be able to give evidence if challenged later

Step 3: Choose the Right Time

If capacity fluctuates:

• Schedule appointments for their best time of day
• Avoid times when they're tired, ill, or in pain
• Keep meetings short
• Be prepared to reschedule if they're not having a good day

Step 4: Document Everything

Keep detailed records of:

• What was discussed and when
• Questions asked and answers given
• Who was present
• The person's demeanour and responses
• Medical assessments

This documentation is crucial if the will is later challenged.

Common Scenarios

Scenario 1: Early-Stage Dementia

Situation: Dad was recently diagnosed with early Alzheimer's. He wants to update his will.

Can he? Very likely yes. Early-stage dementia often leaves testamentary capacity intact. Get a medical assessment and use a solicitor, but there's a good chance this will work.

Scenario 2: Moderate Dementia With Good Days

Situation: Mum has moderate vascular dementia but sometimes has very clear periods.

Can she? Possibly. Schedule the assessment and signing for her best times. Get medical evidence specifically about her lucid intervals. More challenging but potentially valid.

Scenario 3: Advanced Dementia

Situation: Grandad has advanced dementia and doesn't recognise family.

Can he? Almost certainly not. At this stage, testamentary capacity is extremely unlikely. Any will signed would be highly vulnerable to challenge.

What If You Think a Will Was Invalid?

If someone with dementia has died and you believe their will was made without capacity:

Grounds for Challenge

• Lack of testamentary capacity — didn't understand what they were doing
• Undue influence — someone pressured them
• Lack of knowledge and approval — didn't know/approve the contents

Evidence You'll Need

• Medical records around the time of signing
• Evidence of their condition and behaviour
• Witness statements about their state
• The circumstances of the will being made
• Whether proper procedures were followed

Time Limits

Act quickly. While there's no strict time limit for challenging a will, delay weakens your case and the estate may be distributed.

How to Protect Against Future Challenges

If you're helping someone with dementia make a will:

1. Get medical evidence — before and ideally on the day of signing
2. Use a specialist solicitor — not a DIY will or online service
3. Video the signing — with consent, to show their state
4. Have the doctor present — if possible, at the signing itself
5. Keep detailed notes — of every meeting and conversation
6. Explain decisions — especially if excluding expected beneficiaries

What If It's Too Late for a Will?

If capacity has been lost entirely:

• Any existing will remains valid
• If there's no will, intestacy rules apply
• The Court of Protection can make a "statutory will" in rare cases
• Focus shifts to managing their affairs through LPA or deputyship

The Old Way vs Our Way

The Old Way	Our Way
Assume dementia means no will possible	Properly assess capacity — it may still be there
Skip medical assessment to save money	Always get medical evidence
Use a basic will service	Use a solicitor experienced in capacity
Hope no one challenges later	Document everything to prevent challenges