Mutual Wills and Contractual Wills in Queensland: What You Need to Know

Disclaimer — The following guide offers general educational information only and does not constitute legal advice. Mutual- and contractual-will arrangements involve complex contract and estate-law principles. Always obtain personalised advice from a Queensland succession-law solicitor before signing or revoking any binding agreement.

Standard wills can be altered at any time until death. But blended families, second marriages, and high-value estates often call for stronger promises: “If I die first, you’ll keep the will exactly as we agreed.” In Queensland, couples achieve that binding promise through either:

  • Mutual wills – mirror wills reinforced by an enforceable contract not to revoke or amend; or
  • Contractual wills – a single will or pair of wills expressed to be contractual, creating rights for third-party beneficiaries.

Done properly, these mechanisms protect children of earlier relationships, freeze succession plans, and deter later partners from disinheriting step-families. Done badly, they trigger years of expensive litigation. This guide explains the legal foundations, practical advantages, and common pitfalls.


What Are Mutual Wills?

  • Two (or more) testators execute mirror or near-identical wills.
  • A separate binding contract – written or sometimes inferred from conduct – obliges each party not to revoke or change their will without the other’s consent.
  • When the first testator dies, the survivor’s estate is held on a constructive trust for beneficiaries named in the mutual-will contract.
  • Breaching the promise (e.g., by signing a new will) does not invalidate the later will, but equity enforces the trust so that assets still pass to the original beneficiaries.

What Are Contractual Wills?

Queensland’s Succession Act 1981 (s 19) allows a will to incorporate contractual terms. A contractual will:

  • May be single-sided (only one testator) or joint;
  • Creates an explicit contract within the will itself, binding the personal representative not to distribute contrary to the agreement;
  • Gives beneficiaries a chose-in-action (right to sue) if the estate is dealt with inconsistently.

Unlike mutual wills, contractual wills do not rely on constructive trusts; enforcement is by conventional contract remedies.


Core Legal Requirements

RequirementMutual WillContractual Will
Valid contract (offer, acceptance, consideration, intention)Yes – often a separate deed or signed memorandumYes – contractual clause inside will meets s 19 Succession Act
Formality of willsMust satisfy Succession Act execution rulesSame
Proof of intentionMust show clear, irrevocable agreementMust show contractual wording and parties
Enforcement mechanismConstructive trust over survivor’s assetsContract action against estate

Advantages and Disadvantages

ProsCons
PredictabilityProtects children from previous marriages; survivor can’t disinheritRemoves survivor’s flexibility for genuine changed circumstances
Asset protectionDeters predatory later partnersSurvivor may face hardship if asset mix changes
Dispute deterrenceClear evidence of intention reduces will contestsIf wording is unclear, litigation can be longer and costlier than an ordinary Family Provision claim
Tax / Centrelink neutralityNo adverse CGT or duty triggered by agreement itselfMay create trust complications when survivor dies

Practical Situations Suited to Mutual or Contractual Wills

  • Second-marriage spouses each want life-interest for the survivor, then residue to their own children.
  • Unmarried partners with unequal asset pools wishing to preserve gifts to siblings or parents.
  • Farming families where Mum and Dad promise the homestead block to the on-farm child in return for off-farm equalisation.

Drafting Tips for Solicitors

  • Use a standalone deed reciting consideration (e.g., mutual promises or transfer of property) to evidence the contract.
  • State choice-of-law and exclusive jurisdiction (Queensland) to prevent forum shopping.
  • Define “non-revocation” exceptions—for example, both parties can change guardianship clauses but not asset distribution.
  • Address future superannuation: include binding death-benefit nominations or require the survivor to maintain “to estate” nominations.
  • Provide hardship discretion: allow trustee or court variation if survivor’s assets drop below a set threshold.

Common Pitfalls and How to Avoid Them

MistakeResultAvoidance Strategy
Vague oral promise: “We won’t change the wills, okay?”Court finds no enforceable contractExecute written deed contemporaneously with wills
Failure to consider asset substitutionSurvivor sells family home; proceeds outside constructive trustDraft contract to cover “traceable proceeds of substitution assets”
Ignoring future Family Provision claimsDisgruntled child still eligible to claim under s 41 Succession ActInclude provision that each beneficiary acknowledges adequacy; survivor keeps indemnity fund
No disclosure to beneficiariesSurprise at death fuels litigationProvide memorandum of explanation or partial copy of contract to key heirs

Snapshot of Leading Queensland Cases

  • Bigg v Queensland Trustees Ltd [1999] QSC 406 – Court upheld mutual-will agreement and imposed constructive trust over assets sold and repurchased in different form.
  • Forster v Jododex Australia Pty Ltd [2001] QCA 190 – Confirmed that consideration can include mutual promises; no need for money to change hands.
  • Gosper v Gosper [2007] QSC 313 – Survivor’s attempt to revoke and favour new partner failed; trust enforced for children.

Frequently Asked Questions

Can we simply sign “mirror wills” without a contract?
Mirror wills alone are fully revocable. Without a contract or express mutual-will clause, either spouse can change their will tomorrow.

What happens if one spouse remarries after the other dies?
Marriage revokes a will, but it does not dissolve the mutual-will contract. Any new will is subject to the constructive trust; assets must still go to the original beneficiaries.

Can Family Provision claims override mutual wills?
Yes. Eligible applicants may still seek further provision. However, the Court considers the mutual-will obligations when assessing moral duty and often limits extra provision.

Are mutual wills suitable for young couples?
Rarely. They lock both parties into a static plan. Young families typically need flexibility for future children, debts and asset growth.


Key Take-Aways

  • Mutual and contractual wills create legally enforceable promises not to alter testamentary gifts—useful for blended families and asset-protection goals.
  • Success hinges on a clear, written contract executed with the wills, precise drafting and ongoing asset-tracking obligations.
  • They do not block Family Provision claims entirely, but they do shape how the Court balances competing interests.
  • Before signing, weigh the loss of flexibility against the certainty provided to children and other beneficiaries.
  • Professional advice is essential: a poorly worded mutual-will clause can be more damaging than a normal, revocable will.

Sources / References

  1. Succession Act 1981 (Qld) s 19 (contractual wills) & s 41 (family-provision claims).
  2. Bigg v Queensland Trustees Ltd [1999] QSC 406.
  3. Forster v Jododex Australia Pty Ltd [2001] QCA 190.
  4. Gosper v Gosper [2007] QSC 313.
  5. Queensland Law Society, Mutual Wills Practice Guideline (2024).
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Last updated: 30 July 2025

Disclaimer: This information is designed for general information. It does not constitute legal advice. We strongly recommend you seek legal advice in regards to your specific situation. For expert advice call 1300 580 413 or contact us to arrange free initial advice.

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