What is a codicil, and how do you update a will in NZ?

Written by Henry Smith · Reviewed by Smiths Insurance & KiwiSaver, licensed Financial Advice Provider (FSP712931) · Updated 2026-10-20 · Reviewed annually, or sooner if the rules it describes change.

A codicil is a formal amendment to an existing will, used to change part of it without rewriting the whole document. The Ministry of Justice describes it as "a formal amendment to a will", and says the same requirements apply to a codicil as to the will itself. In New Zealand that means the Wills Act 2007: it must be in writing, signed by the will-maker, and witnessed by at least two people who are together in the will-maker's presence (Wills Act 2007, s 11).

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How does a codicil change a will?

A codicil is a separate short document that refers to the will and alters it: it names a new executor, changes a gift, or corrects a detail. The Act includes a codicil within its meaning of "will" for most purposes (s 8(3)(e)), and it treats a codicil that revives a revoked will as needing to comply with s 11 (s 17(1)(b)). We found no separate formalities for stand-alone codicils in the Act, so the safe course is to sign and witness one exactly as you would a will.

The Act also lists the ways a valid will can be changed. A change is valid only if it is:

written on the will and signed and witnessed beside the change; or
a note written on the will, signed and witnessed; or
an obliteration of words so that their effect is not apparent; or
declared valid by the High Court under s 14, which allows it to accept a document that does not comply with the formalities if it expresses the deceased's testamentary intentions (s 15); or
done under s 34(2), a route outside the scope of this guide (s 15(e)).

That list is why scribbling on a will is risky. A handwritten amendment that is not signed and witnessed properly is unlikely to take effect without a court declaration.

The signing rules, step by step

Put it in writing, and sign it, or direct someone to sign it for you in your presence (s 11(3)).
Have at least two witnesses together in your presence when you sign or confirm your signature, and each witness signs in your presence (s 11(4)).
Choose the witnesses carefully. The Act has no rule that a witness must be "independent", and an executor may witness (s 12). But a gift in the will to a witness, or to a witness's spouse or partner, is void unless the will has at least two other witnesses who are not connected, or the other narrow exceptions apply (s 13). The Ministry of Justice's checklist tells applicants a witness "should not be someone who receives a gift".
Keep it with the will. The court expects the original will and any codicil. See below.

The Ministry of Justice says having the will-maker and both witnesses sign each page at the bottom is not a legal requirement, but is considered best practice because it helps show no page was added or replaced.

Codicil or new will?

	Codicil	New will
Suits	One small, clear change	Several changes, or changes to the main gifts
What the court reads	The will and the codicil together	One document
Cost	We found no published price for a codicil	PK Law lists a simple single will at $750 plus GST and a couple's will at $1,250 plus GST (complexity level 1)
Main risk	Two documents can be misread together, or one can go missing	Forgetting to revoke the old will clearly
Marriage or civil union	Does not save the will by itself; a will survives only if it was made in contemplation of that marriage or civil union (s 18(3))	A new will that says it is made in contemplation of the marriage is not revoked by it (s 18(3))

Sources: Wills Act 2007, PK Law pricing, retrieved 20 October 2026.

A new will that clearly revokes earlier ones is the cleaner route in most cases where more than one thing changes. A later valid will revokes an earlier one (s 16(a)). That is our reading of the trade-offs, not a rule of law. Ask the lawyer to quote for both a codicil and a new will before you decide.

Mistakes and risks to watch for

Marriage or civil union. A will is revoked if the will-maker marries or enters a civil union, unless it was made in contemplation of that particular marriage or civil union (s 18). A codicil is not the usual fix: the Act lets a revoked will be revived only by signing it again with the formalities, or by a codicil that makes clear the intention to revive and is signed and witnessed as a will is (s 17(1)), so ask a lawyer whether a new will is simpler. After a dissolution or separation order, gifts and appointments to the former partner are void unless the will shows otherwise (s 19).
Gifts to witnesses being void (s 13), as above.
Mismatched details. The court's probate guide says the applicant must use the wording exactly as it appears in the most recent signed will or codicil, including the deceased's place of residence and occupation.
A codicil that changes the executor. Applicants must say clearly that they are the executor named in the codicil.
Marks on the original. The Ministry of Justice says the High Court must be satisfied that nothing has been attached to or taken out of the original will, and its checklist asks about pinholes and staple marks. Ask your lawyer how to store a will and codicils together.
A lost codicil. The court asks for the original will and the original codicil, so keep them where the executor can find them, and tell the executor and your lawyer where that is. If one cannot be found, ask a lawyer what the court will accept.

How a codicil is handled at probate

When an executor applies for probate, the Ministry of Justice lists the documents as the application, an affidavit, the original will and "original codicil(s) (changes made to the will) if applicable". The same checks apply to a codicil as to the will (Ministry of Justice: Applying for probate, a practical guide). Once an application is filed, the court file is public, including the will and any codicil; see who is entitled to a copy of a will and probate records search. For the process, see probate in New Zealand.

Check the rest of your paperwork as well

Changing a will does not necessarily change everything else. Who receives a life insurance payout depends on who owns the policy and the insurer's terms, and it reaches the estate only if it is payable there (Community Law). After a change of circumstances, check the policy as well as the will. See who gets your life insurance payout and making a will in NZ.

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