Last Updated on April 30, 2026 by tanya

What Makes a Codicil Valid?

 

About Our Legal Expert: This content is produced under the oversight of Michael Jefferies, First Personal Injury Director, who brings over 30 years of legal experience.

Written by Tanya Waterworth, Digital Content Writer

 

How Common Codicil Mistakes Trigger Will Disputes

It may be tempting to add a codicil to a will instead of rewriting the entire document, but what makes a codicil valid? Many people think it’s a simple addition or change, but it’s vital that a codicil is executed correctly. In fact, there are common codicil mistakes which may lead to contentious probate claims in England and Wales.

If you are facing a will challenge – or defending one – due to a codicil, contentious probate claims can be complex. So, it’s advisable to seek legal guidance.

 

Amending a Will With a Codicil?

A codicil is a legal document that amends, rather than replaces, an existing will. You might use a codicil to:

 

• Change an executor
• Add or remove a beneficiary
• Update a specific gift
• Amend a trust provision
• Reflect a change in personal circumstances

 

A codicil forms part of your will once properly executed. The court reads it together with the original will during probate.

However, a codicil has to meet strict legal requirements.

 

What Makes a Codicil Valid in England and Wales?

The validity of a codicil falls under the same formal requirements as a will under the Wills Act 1837. If you fail to comply, the codicil will be invalid.

To ensure validity, you must ensure the following:

 

1. The Codicil Must Be in Writing

A codicil must be written. Oral changes to a will are not legally binding in England and Wales, except in extremely limited circumstances (for example,  privileged wills for armed forces personnel).

 

2. The Testator Must Have Testamentary Capacity

The person making the codicil (the testator) must:

 

• Understand they are making changes to their will
• Understand the nature and extent of their estate
• Understand who might reasonably expect to benefit
• Be free from any disorder of the mind that affects decision-making

 

Disputes frequently arise when codicils are executed later in life, particularly where capacity becomes questionable.

 

3. The Codicil Must Be Signed

The testator must sign the codicil, or someone else must sign on their behalf in their presence and at their direction.

 

4. Two Independent Witnesses Must Be Present

Two witnesses must:

 

• Be present at the same time
• Witness the testator’s signature
• Sign the codicil themselves

 

Witnesses must be independent, i.e. cannot be a beneficiary, or the spouse of a beneficiary.

 

5. The Testator Must Intend the Document to Amend the Will

The testator must intend the codicil to operate as a testamentary amendment. Ambiguous notes, side letters, or unsigned drafts do not qualify.

 

 

How Common Codicil Mistakes Can Trigger Probate Disputes

While codicils appear simple, they can often spark a will dispute. Here are some of the  most common mistakes that lead to contentious probate claims in England and Wales.

 

Improper Execution

Failure to comply strictly with the Wills Act 1837 invalidates the codicil.

Typical errors include:

 

• Witnesses signing separately
• A beneficiary acting as witness
• Missing signatures
• Using digital or electronic signatures

 

When execution is defective, disputes arise over whether the codicil should be admitted to probate. Interested parties may challenge its validity, particularly if it alters substantial gifts.

 

Lack of Testamentary Capacity

Capacity challenges frequently arise where codicils are made shortly before death.

If medical records suggest cognitive decline, dementia, or confusion, disappointed beneficiaries may contest the codicil.

Because codicils often introduce targeted changes, for example excluding a family member, they attract scrutiny. A late-stage amendment that significantly benefits one individual can give rise to allegations of incapacity.

 

Undue Influence

Codicils can create fertile ground for undue influence claims. However, undue influence in probate requires proof of coercion – not mere persuasion. So, when a codicil benefits a carer, new partner, or recently involved individual, family members may allege pressure.

If the codicil appears inconsistent with longstanding testamentary intentions, the court may examine surrounding circumstances carefully.

 

Ambiguous Drafting

Many individuals draft codicils without professional assistance. But, poor drafting may create ambiguity, especially where the codicil:

 

• Fails to identify the correct clause in the original will
• Refers vaguely to “my previous gift”
• Uses inconsistent terminology
• Partially revokes a clause without clarity

 

If there’s ambiguity, the court must then interpret how the codicil interacts with the will,

 

Failing to Consider the Doctrine of Republication

When a codicil is properly executed, the original will is treated as if it were executed on the same date as the codicil. In other words, the will is “brought up to date” as of the codicil’s execution. So, when a codicil republishes a will, it may affect:

 

• After-acquired assets
• Executor appointments
• Guardianship provisions
• Tax planning structures

 

Inconsistent Multiple Codicils

Over time, some testators accumulate several codicils. These may lead to problems when later codicils contradict earlier ones, or amendments overlap.

In these cases, executors must reconcile competing provisions. If the documents conflict, beneficiaries may issue probate claims to determine which terms prevail.

 

Failing to Update the Entire Will When Needed

Codicils suit minor amendments. They do not suit substantial restructuring.

If you attempt to use a codicil to overhaul complex trusts, alter multiple beneficiaries, or change residue distribution, you increase the risk of internal inconsistency.

Courts often see disputes where a codicil attempts to “patch” an outdated will instead of replacing it entirely.

 

Storage and Discovery Issues

A codicil must be located after death. If executors discover a codicil stored separately from the will, disputes can arise over authenticity.

Where the original will appears intact but a later codicil cannot be found, arguments may arise about whether the testator destroyed it intentionally.

 

When Should You Use a Codicil?

A codicil may work well where you:

 

• Replace one executor
• Amend a small cash gift
• Correct a minor administrative error

 

However, you should consider drafting a new will if:

 

• Your estate structure has changed significantly
• You have married or divorced
• You wish to exclude a close family member
• You need complex tax planning

 

Essentially, a new will often reduces the likelihood of disputes.

 

Free Consultation – Take The Next Step Now

Codicils offer a convenient way to amend a will, but in practice, codicils can frequently trigger probate disputes because they introduce targeted, often last-minute changes. Improper execution, ambiguous drafting, and capacity concerns commonly form the basis of contentious probate claims.

If you need legal advice regarding a contentious probate claim involving a codicil, our panel of contentious probate lawyers are highly experienced and also offer a range of fee structures, including ‘No Win, No Fee’ for certain cases along with other flexible funding.

Call us at 0333 358 2345 or contact us online for a free consultation.