In short
A will is invalid if it was not in writing, signed, and witnessed by two witnesses present at the same time, unless a court exercises the dispensing power. It can also be revoked without anyone intending it: marriage revokes a will in both jurisdictions, and divorce revokes the gifts and appointments in favour of the former spouse. Capacity is governed by the general law and is not defined in either Act.
- In the ACT the witnesses must sign in each other's presence. In New South Wales they need not.
- A gift to an attesting witness is void in New South Wales and expressly not void in the ACT.
- Marriage revokes a will in both. Only New South Wales saves a will made in contemplation of a marriage that the will does not mention.
- A change in circumstances revokes nothing: section 11(2) closes that argument off.
Most worries about an invalid will are about the wrong thing
Two quite different questions get asked in the same words. One is whether the will is valid, which is about how it was made and whether anything has since revoked it. The other is whether someone left out of it can do something about that, which is a family provision claim and has nothing to do with validity at all. A will can be perfectly valid and still be challenged successfully by a person the testator did not provide for.
This article is about the first question only. It sets out what actually makes a will invalid in New South Wales and the Australian Capital Territory, and what quietly revokes one that was valid when it was signed.
The two jurisdictions look similar and are not. On one point that comes up constantly, a gift to a witness, they produce opposite results on identical facts.
ExecutionSection 6 of the Succession Act 2006 (NSW) and section 9 of the Wills Act 1968 (ACT). In writing, signed, and the signature made or acknowledged before two or more witnesses present at the same time. The ACT additionally requires each witness to subscribe in the presence of the other witnesses; New South Wales expressly does not.
Figure 1. The first three ask whether the will was ever valid. The last three revoke one that was, and they account for far more failed estate plans than any defect in signing.
Execution: what the two Acts actually require
The formal requirements are short, and almost every homemade will that fails, fails on one of them.
Table 1. Execution requirements. Section 6 of the Succession Act 2006 (NSW) and section 9 of the Wills Act 1968 (ACT).
| New South Wales, s 6(1) | ACT, s 9(1) |
|---|
| Form | In writing | In writing |
|---|
| Signature | By the testator, or by another person in the presence of and at the direction of the testator | Same, but signed at the foot or end |
|---|
| Witnesses | Signature made or acknowledged in the presence of 2 or more witnesses present at the same time | Same |
|---|
| Attestation | At least 2 of those witnesses attest and sign in the presence of the testator, but not necessarily in the presence of each other | 2 or more attest and subscribe in the presence of the testator and of the other witness or witnesses |
|---|
| Attestation clause | Not essential, s 6(3) | No form of attestation required, s 9(2) |
|---|
Two of those differences matter in practice.
Whether the witnesses have to sign in front of each other. New South Wales says expressly that they do not. The ACT provision requires each witness to subscribe in the presence of the testator and of the other witness or witnesses. A will signed by two witnesses who came in one after the other satisfies section 6 in New South Wales and is a problem under section 9 in the ACT.
Where the signature goes. Section 6(2) in New South Wales says the signature must be made with the intention of executing the will and that it is not essential for it to be at the foot. The ACT provision says "at the foot or end", but section 10(1) softens it: the position of the signature does not invalidate the will if it is apparent on the face of the will that the testator intended to give effect by that signature to the writing signed as their will.
One thing that does not matter in either jurisdiction is whether the witnesses knew what they were signing. Section 7 in New South Wales says so expressly, and section 14 in the ACT provides that a will is not voided by the incompetence of a witness.
A document that fails the formalities can still be a will
Both jurisdictions have a dispensing power, and it is wider than most people expect. It is the reason a note, a draft, an unsent letter or a document on a phone can end up admitted to probate.
Section 8 of the Succession Act 2006 (NSW) applies to a document, or part of a document, that purports to state the testamentary intentions of a deceased person and has not been executed in accordance with the Act. That document forms the will, or an alteration to it, or a full or partial revocation of it, if the Court is satisfied that the person intended it to. Section 11A of the Wills Act 1968 (ACT) is to the same effect.
What the Court may look at is the significant part. Under section 8(3) it may have regard, in addition to the document itself, to any evidence relating to the manner in which the document was executed and to any evidence of the testamentary intentions of the deceased, including evidence of statements made by them. Section 8(4) makes clear that this does not limit what else may be considered. The ACT provision carries the same two heads.
What this means for you
The dispensing power cuts both ways and neither way is comfortable. If a properly executed will exists, an informal later document can be argued to have altered or revoked it. If it does not, a family may find themselves litigating about whether a draft was intended to operate. Either way the outcome turns on evidence of intention rather than on the document, which makes it expensive and unpredictable. It is a safety net, not a plan.
A gift to a witness: the two jurisdictions go opposite ways
This is the single most useful thing to know if you act, or advise, across the border.
In New South Wales, section 10 provides that where a beneficial disposition is given by will to a person who attests the execution of the will, the disposition is void to the extent that it concerns that interested witness or anyone claiming under them. The gift fails; the will does not.
Section 10(3) saves the gift in three situations:
- at least two of the people who attested are not interested witnesses; or
- everyone who would benefit directly from the avoidance consents in writing to the distribution under the will, and has capacity to consent; or
- the Court is satisfied the testator knew and approved of the disposition and that it was given freely and voluntarily.
Section 10(4) confines what counts as a beneficial disposition: it does not include a charge or direction to pay a debt, or reasonable remuneration to an executor, administrator or legal practitioner acting in the administration.
In the ACT, section 15 of the Wills Act 1968 says the opposite in one sentence. No will or testamentary provision is void by reason only that the will was attested by a person, or the domestic partner of a person, who has or may acquire an interest under it. Sections 18 and 19 add that a creditor and an executor are each admitted as a witness.
Table 2. The same facts, the opposite result. A will witnessed by two people, one of whom is a beneficiary.
| New South Wales | ACT |
|---|
| The will | Valid | Valid |
|---|
| The gift to the witness | Void, unless s 10(3) saves it. With only two witnesses and one of them interested, limb (a) cannot apply | Not void, s 15 |
|---|
| If the witness is the beneficiary's partner | Not caught by s 10, which is about the witness's own interest | Expressly not void, s 15 |
|---|
None of which is a reason to have a beneficiary witness a will anywhere. It is a reason to check which side of the border the will was signed on before advising that a gift has failed.
Age, and the exceptions nobody remembers
A will made by a minor is not valid, and both Acts then carve out the same handful of cases. Section 5(1) of the Succession Act says a will made by a minor is not valid. Section 8(1) of the Wills Act 1968 says the same of a child.
The exceptions in New South Wales, in section 5(2), are a will made in contemplation of marriage, which is of no effect if the contemplated marriage does not take place; a minor who is married; and a minor who has been married revoking a will made while married or in contemplation of that marriage. Section 5(3) preserves a court-authorised will under section 16.
The ACT is the same in structure and wider in its trigger, because section 8 extends to a civil union as well as a marriage: a child who is or has been married or in a civil union may make or revoke a will, and a will made in contemplation of a marriage or civil union becomes valid on solemnisation or entry.
Capacity, which neither Act defines
Testamentary capacity is the ground most wills are actually challenged on, and it is not in either statute. Neither the Succession Act 2006 (NSW) nor the Wills Act 1968 (ACT) sets out a test. Both legislate around the concept: each has provisions allowing the Supreme Court to authorise a will for a person who lacks testamentary capacity, which presuppose the concept without defining it.
Capacity is governed by the general law, and the test is not set out in this article. That is deliberate: it comes from case law, the authorities on it were not read for this piece, and a half-remembered statement of a four-limb test is exactly the kind of thing that should not be published. If capacity is in issue, it is a question for advice on the medical and factual evidence rather than something to be resolved from an article.
What is worth saying is when it becomes an issue. Capacity is assessed at the time the will was made, not later. A diagnosis does not decide it and neither does age. What decides it is contemporaneous evidence, which is why a will prepared while capacity is deteriorating should be made with a file note, a medical opinion taken at the time, and a record of the instructions. Those are cheap to create then and impossible to create afterwards.
What revokes a will without anyone intending it
Two life events revoke a will or part of it by operation of law, and this catches more valid wills than any defect in execution.
Marriage
In New South Wales, section 12(1) provides that a will is revoked by the marriage of the testator. Section 12(2) preserves a disposition to the person the testator is married to at death, an appointment of that person as executor, trustee, advisory trustee or guardian, and a will exercising certain powers of appointment. Section 12(3) is the important escape: a will made in contemplation of a particular marriage is not revoked by that marriage, whether or not the contemplation is expressed in the will.
In the ACT, section 20(1) extends the trigger to a civil union or civil partnership as well as marriage, and narrows the escape: the will survives only where it was expressed to have been made in contemplation of that marriage, civil union or civil partnership. A New South Wales will that relies on unexpressed contemplation would not be saved by the ACT provision.
Divorce or termination
Section 13(1) of the Succession Act provides that divorce or annulment revokes a beneficial disposition to the former spouse, an appointment of them as executor, trustee, advisory trustee or guardian, and a grant of a power of appointment exercisable by or in favour of them. Section 13(2) makes that subject to a contrary intention appearing in the will, and section 13(3) preserves their appointment as trustee of property left on trust for beneficiaries including their children, and a power of appointment exercisable exclusively in favour of the children of both.
Section 20A of the Wills Act 1968 does the equivalent in the ACT on the termination of a marriage, civil union or civil partnership.
What this means for you
If you have married, entered a civil union or divorced since your will was signed, the will you think you have is probably not the will you have. This is the most common way a carefully prepared estate plan stops working, and it is entirely avoidable: it takes one review.
How a will is deliberately revoked
The list is closed, and it is shorter in the ACT.
Section 11(1) of the Succession Act 2006 (NSW) provides that the whole or part of a will may be revoked only: by an order under section 16 or 18; by the operation of section 12 or 13; by a later will; by writing declaring an intention to revoke, executed in the manner a will must be executed; by the testator, or someone in their presence and at their direction, burning, tearing or otherwise destroying the will with the intention of revoking it; or by writing on or dealing with the will in such a way that the Court is satisfied from the state of the will that the testator intended to revoke it.
Section 11(2) closes off the argument people most often try: no will may be revoked by any presumption of an intention on the ground of an alteration in circumstances. A change in the family, in the assets or in the relationship revokes nothing.
Section 21 of the Wills Act 1968 (ACT) is to similar effect but has no equivalent of the sixth New South Wales limb. In the ACT, revocation is by a subsequent valid will, a document executed like a will showing an intention to revoke, or destruction with that intention. There is no "state of the will" route.
The will the Court makes
Where a person has lost capacity, a will can still be made for them, but only by the Supreme Court and only on a strict test.
In New South Wales, section 18(1) allows the Court, on application by any person, to authorise a will to be made or altered in specific terms it approves, or revoked, on behalf of a person who lacks testamentary capacity. Leave is required under section 19, and section 18(3) requires the person to be alive when the order is made. Section 18(4) extends it to a minor who lacks capacity.
In the ACT, section 16A does the equivalent, and section 16E sets out what the Court must be satisfied of before granting leave: that there is reason to believe the person is, or is reasonably likely to be, incapable of making a will; that the proposed will is, or is reasonably likely to be, one that would have been made by the person if they had capacity; that it is or may be appropriate; that the applicant is an appropriate person; and that adequate steps have been taken to allow representation of everyone with a legitimate interest, including anyone with reason to expect a gift.
The second of those is the substance of the exercise. The Court is not deciding what would be fair. It is reconstructing what this person would have done.
Where this article stops
Not covered, and not to be assumed
- The test for testamentary capacity. It comes from case law, no authority was read for this article, and it is therefore not stated. If capacity is in issue, take advice on the evidence.
- Undue influence, and knowledge and approval. Both are general law grounds, and both are outside what was verified here.
- Family provision claims. A person left out of a valid will may still apply for provision from the estate. That is a separate regime with its own time limits and it is not about validity, which is why it is not in this article.
- Wills with a foreign element. Part 2A of the Wills Act 1968 (ACT) contains rules on the formal validity of a will made outside the territory, and cross-border estates raise questions this article does not reach. We have written separately on international assets and beneficiaries.
- Any jurisdiction other than New South Wales and the ACT. Each state has its own Act, and the differences between these two show how little can safely be carried across a border.
The position stated is as at 27 August 2026, read on that date from the Succession Act 2006 (NSW) in force consolidation and from republication 22 of the Wills Act 1968 (ACT), effective 23 February 2026.