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How to update your UK will with a codicil

In short. A codicil is a short amendment to an existing will, signed and witnessed in the same way as a full will (two adult witnesses, not beneficiaries). Use it for small changes; rewrite the will for anything substantial.

A codicil is a legally valid addition or amendment to an existing will. It must satisfy the same s9 Wills Act 1837 formalities — written, signed by you in the joint presence of two adult witnesses, and signed by them in your presence. Multiple codicils on one will quickly become confusing; for major changes, rewrite.

Last reviewed:

·Estimated time: 3 days·Cost: £20–£100 (solicitor) or £0 DIY

What you'll need

  • Original will
  • Two adult witnesses (not beneficiaries or their spouses)

The steps

  1. 01

    Decide if a codicil is right

    Codicils suit small, clear changes — replacing one executor, adjusting a single legacy, adding a recent grandchild. Anything affecting the residue, multiple clauses, or the structure of the will is safer in a rewrite. For a rewrite, an online service such as Swiftwill (from £90, advertised as around 20 minutes) is often quicker and cheaper than a second solicitor visit.

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  2. 02

    Draft the codicil

    Identify the original will by date, state exactly what is being changed, added or revoked, and confirm that everything else in the original will remains in force. Use a solicitor for anything beyond a one-line change.

  3. 03

    Sign in front of two witnesses

    Sign in ink in the joint presence of two adult witnesses who are not beneficiaries (or married to a beneficiary). Both witnesses then sign in your presence. The witnesses do not need to be the same as those on the original will.

    Official link →

  4. 04

    Store with the original will

    Keep the signed codicil with the original will. Do not staple, pin or otherwise attach it — the probate registry treats marks on the original as evidence of a possibly missing document. Use a paper clip or store loose in the same envelope.

  5. 05

    Tell your executors

    Let your executors know a codicil has been added. They need both documents at probate, and a codicil that surfaces after probate has been granted causes delays and costs.

Common pitfalls

  • Witnessing the codicil with a beneficiary — under s15 Wills Act 1837 their gift fails even though the codicil itself is valid
  • Stacking multiple codicils on one will — quickly leads to ambiguity. After two codicils, rewrite the will
  • Treating a codicil as a way to add a new spouse after marriage — marriage automatically revoked the prior will in England and Wales, so a codicil on a revoked will is itself invalid
  • Failing to identify the will by date — an ambiguous codicil may be ignored at probate

FAQ

When should I rewrite the will instead?
Any change that touches the residue, multiple clauses, or the structure of the will. Most solicitors rewrite for any change beyond a single legacy or executor swap — a new will is clearer and only marginally more expensive.
Can I write a codicil myself?
Yes — the s9 formalities are the same. But the same risks apply as DIY wills: unclear wording, witnessing errors and conflicts with the original. For anything other than a one-line change, use a solicitor.
Does marriage revoke a codicil?
Yes — marriage revokes both the will and any codicils in England and Wales, unless made 'in contemplation of' that marriage. If you remarry, make a new will, not a codicil.
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