Unfortunately there is no simple yes or no answer to this question. There’s no hard-and-fast rule, and can vary case-by-case.
But here is some information that can help you if you, or someone you know, wants to write a will with a diagnosis of dementia.
You can write or amend a will if you have dementia as long as you have what's called ‘testamentary’ capacity.
Your capacity to write a will isn’t exactly the same as ‘mental capacity’ as it’s defined under the Mental Capacity Act 2005 (although there is some overlap).
You have ‘testamentary capacity’ if you are able to understand the following at the time of writing or amending your will:
N.B There is no obligation to leave them anything but you must understand the validity and basis of their reasoning, and be aware that under the Inheritance (Provision for Family and Dependants) Act 1975, someone that is dependent on you is entitled to challenge the fact that they’ve been excluded from your will.
If you have testamentary capacity: If you tick of the boxes above and you have testamentary capacity to write a will with dementia you can do in all of the usual ways:
The only added step is that it’s worth getting your GP or a medical expert to provide a note attesting to your testamentary capacity before you write your will.
Additionally, it helps to have your GP witness your will when signing.
This reduces the risk of your will being contested and makes life easier for everyone involved.
If you lack testamentary capacity:
You can still have a will in place.
To do this, someone can apply to the Court of Protection who will make a statutory will on your behalf. They are obliged to act in your best interests and will consider your past and present wishes, as well as any values or beliefs that could have influenced your decision if you still had capacity. This is easier to do when the testator has never made a will before or if there have been major changes to their life’s circumstances.
Yes. It is possible to write a will when you have dementia - as long as you have testamentary capacity.
Even if you no longer have testamentary capacity there are ways of having a will via the Court of Protection.
A person with dementia can sign a legal document such as a will. Their signature is valid as long as they have testamentary capacity’.
As with all wills it is only valid if the testator signs the will in the presence of two independent witnesses and they in turn sign in the presence of the testator. These witnesses can’t be beneficiaries of the will and must be over the age of 18.
If there are physical issues that make signing the will difficult or impossible then the testator can ask someone else to sign the will on their behalf providing it is in their presence and they (the testator) has capacity. This signature is also legally valid thanks to the Wills Act 1837.
A person with dementia can change their Will as long as they have testamentary capacity.
Find out more information about what constitutes testamentary capacity above.
As with any will - any big changes require previous wills to be revoked (include link to article about revocation “What can make a will invalid”). This includes things like changing the division of your estate.
Smaller amends - such as changing your executors can be done through a ‘codicil’, or just simply updating your online will and submit it for review.
Both changes require the testator to sign it with two independent witnesses who are +18 years of age.
As long as the testator has testamentary capacity there is no issue with this.