UK adults whose circumstances change after making a will need to know how to update it correctly, because an informal change can fail. This guide explains updating a will in England and Wales: what a codicil is, when a full rewrite is better, the witnessing rules that apply, and why crossing out a will does not work. It cites the Wills Act 1837 and Money Helper. Kael Tripton is an editorial publisher and not a regulated legal services provider. This article is information only and is not legal advice. Anyone updating a will should consult an SRA-authorised solicitor or Citizens Advice.
Key Facts
- A codicil is a separate document that amends an existing will rather than replacing it (Money Helper, accessed June 2026).
- A codicil must be signed and witnessed with the same formalities as a will under the Wills Act 1837 (Wills Act 1837, legislation.gov.uk).
- You cannot validly change a will by crossing things out or writing on it after it has been signed (Money Helper, accessed June 2026).
- For major changes, a new will that revokes the old one is usually clearer than a codicil (Money Helper, accessed June 2026).
- Marriage usually revokes an existing will unless it was made in contemplation of that marriage (Wills Act 1837, legislation.gov.uk).
- A will should be reviewed after major life events such as marriage, divorce, births, and significant changes in assets (Money Helper, accessed June 2026).
Why wills need updating
A will reflects a person's circumstances and wishes at the time it was made, and both change over time. Marriages, divorces, new children or grandchildren, the death of a beneficiary or executor, house moves, and changes in the value or type of assets can all make an existing will out of date (Money Helper, accessed June 2026). A will that no longer matches a person's situation can produce results they would not have chosen, or can leave gaps that fall into the intestacy rules.
Some life events change a will automatically. Marriage or entering a civil partnership usually revokes an existing will entirely, unless that will was made in contemplation of the marriage (Wills Act 1837, legislation.gov.uk). Divorce does not revoke the whole will but treats a former spouse as having died for gifts and appointments to them. Because of these effects, reviewing a will after any major life event, rather than assuming it still works, is part of keeping an estate plan reliable.
Codicils and full rewrites
There are two main ways to update a will. A codicil is a separate document that amends specific parts of an existing will while leaving the rest in place. It suits small, clear changes, such as changing an executor or adjusting a single gift (Money Helper, accessed June 2026). A full rewrite replaces the existing will with a new one that includes a clause revoking all earlier wills and codicils, and suits larger or multiple changes.
The choice between them is about clarity. A single codicil on a simple point is convenient, but several codicils over time can make a will confusing and harder to interpret after death, raising the risk of dispute. Where the changes are significant, or where more than one or two have built up, a new will is usually cleaner. Both routes must be executed with the same care as the original will, because an improperly made codicil or rewrite can fail (Wills Act 1837, legislation.gov.uk).
The process step by step
- Review the existing will. Identify exactly what needs to change and whether the change is minor or substantial (Money Helper, accessed June 2026).
- Choose a codicil or a new will. Use a codicil for a small, clear change, or a new will for larger or multiple changes (Money Helper, accessed June 2026).
- Draft the change clearly. Set out the amendment precisely, referring to the original will where a codicil is used (Money Helper, accessed June 2026).
- Sign and witness it. Execute the codicil or new will with two independent witnesses present at the same time, as required by the Wills Act 1837 (legislation.gov.uk).
- Revoke the old will if rewriting. A new will should include a clause revoking all earlier wills and codicils, and the old document can be destroyed (Money Helper, accessed June 2026).
- Store and inform. Keep the updated documents with the will and tell the executors where they are (Money Helper, accessed June 2026).
Common mistakes when updating a will
The most serious mistake is trying to change a will informally. Crossing out words, writing new instructions in the margin, or attaching a note does not validly amend a will, and any unwitnessed alteration made after the will was signed is generally disregarded (Money Helper, accessed June 2026). The original wording usually stands, which can defeat the change the person intended.
Another common error is making a codicil that is not properly witnessed, which leaves the amendment invalid even though the change was clearly intended. Allowing multiple codicils to accumulate, so that the will and its amendments contradict or confuse each other, is a further problem. Forgetting to revoke an old will when making a new one can leave two documents in existence, creating uncertainty about which applies. Following the same formalities as the original will, and keeping the documents together, avoids these issues.
How this connects to wills and probate
Updating a will follows the same execution rules covered in how to write a will and the detailed witness requirements, because a codicil or new will must be signed and witnessed in the same way. Keeping documents current is the same discipline that applies to mirror wills, where each partner can change their own will over time.
The point of keeping a will up to date is to control what happens at probate. The document in force at death is the one the executors prove and follow, so an out-of-date or improperly amended will can produce an outcome the person did not intend, or can throw part of the estate into intestacy. A clear, current will makes the later probate process simpler and reduces the risk of a dispute.
When to use a solicitor versus doing it yourself
A simple codicil, such as changing an executor, can be made without a solicitor as long as it is signed and witnessed correctly (Money Helper, accessed June 2026). For a single, clear change to an otherwise sound will, this route keeps the cost down.
A solicitor becomes more useful for substantial changes, for situations where several amendments have built up, or where the change affects tax planning, trusts, or provision for a blended family. A solicitor can advise whether a codicil or a new will is the better route and ensure the revocation of earlier documents is handled properly. The Law Society and the Solicitors Regulation Authority maintain registers of authorised solicitors (lawsociety.org.uk and sra.org.uk, accessed June 2026). The decision depends on how significant and how numerous the changes are.
FAQ: updating a will and codicils
What is a codicil?
A codicil is a separate legal document that amends part of an existing will without replacing the whole thing (Money Helper, accessed June 2026). It must be signed and witnessed with the same formalities as a will under the Wills Act 1837 (legislation.gov.uk). Codicils suit small, clear changes such as changing an executor or adjusting a single gift, rather than major revisions.
Can I just cross out part of my will and write a change?
No. Crossing out words or writing new instructions on a will after it has been signed does not validly change it, and unwitnessed alterations are generally disregarded (Money Helper, accessed June 2026). The original wording usually stands. To make a valid change, you need a properly executed codicil or a new will that meets the Wills Act 1837 rules (legislation.gov.uk).
Should I use a codicil or write a new will?
A codicil suits a small, single change, while a new will is usually clearer for larger or multiple changes (Money Helper, accessed June 2026). Several codicils over time can make a will confusing and raise the risk of dispute after death. Where changes are significant, a new will that revokes all earlier wills and codicils is generally the cleaner option.
Does my will need updating after marriage or divorce?
Yes. Marriage or entering a civil partnership usually revokes an existing will entirely unless it was made in contemplation of that marriage (Wills Act 1837, legislation.gov.uk). Divorce treats a former spouse as having died for gifts and appointments to them. Both events should prompt a review, and often a new will, to ensure the estate passes as intended.
Do codicils need witnesses?
Yes. A codicil must be signed and witnessed in the same way as a will, with two independent witnesses present at the same time who then sign themselves (Wills Act 1837, legislation.gov.uk). A codicil that is not properly witnessed is invalid, even if the intended change was clear. The same independence rules apply, so a beneficiary should not witness it.
