Guide
Quantum Meruit in Australia: Getting Paid Without a Contract
What the claim is, how the number is assessed, and why Mann v Paterson changed the arithmetic.
In short
Quantum meruit means "as much as he has deserved". It is a restitutionary claim for the reasonable value of work you performed where no enforceable contract price covers it. Since Mann v Paterson Constructions [2019] HCA 32, the contract rate generally caps what you can recover.
Quantum meruit is the claim businesses reach for when the paperwork has failed them: work was done, the other side had the benefit of it, and there is no signed scope or price that says what it was worth. It is a real cause of action — and a far worse position than simply having a contract.
What the Claim Actually Is
Quantum meruit is not a claim for breach of contract. It is restitutionary: you say the other party has been enriched at your expense, in circumstances where it would be unjust for them to keep the benefit without paying for it. The three elements a court looks for are:
- A benefit was conferred on the defendant (services performed, goods supplied, land improved).
- The benefit was at the plaintiff's expense.
- Retention of the benefit without payment would be unjust — typically because it was requested, accepted, or freely accepted with knowledge that payment was expected.
When It Is Available
| Situation | Claim to run |
|---|---|
| Signed contract with a price for the work | Sue on the contract — quantum meruit is not open |
| Work started on a letter of intent, contract never signed | Quantum meruit |
| Contract void, illegal or unenforceable | Quantum meruit |
| Extra work performed at request, outside scope | Variation claim first; quantum meruit as fallback |
| Principal repudiated and you terminated | Damages, or quantum meruit within the Mann v Paterson limits |
How the Amount Is Assessed
"Reasonable value" is an objective question, not your invoice. Courts look at market rates for the labour, plant, materials and supervision actually applied, usually proved by:
- Timesheets, site diaries and delivery dockets contemporaneous with the work
- Purchase orders and subcontractor invoices
- Comparable quotes or rate schedules from the same period
- Expert quantity surveying or valuation evidence
Profit and overhead are recoverable to the extent they form part of a reasonable market price, but a quantum meruit claim is not an invitation to price the job again with hindsight.
Mann v Paterson: The Cap
Before 2019, a builder who accepted a principal's repudiation could sometimes recover a quantum meruit assessment that exceeded the contract price — an uncomfortable outcome, because the innocent party ended up better off than performance would have left them. In Mann v Paterson Constructions Pty Ltd [2019] HCA 32 the High Court restricted that:
- Where a contractual right to payment had already accrued for a stage of work, the claim is on the contract, not in restitution.
- For work in progress at termination, restitution may be available, but the contract rate operates as a ceiling on the reasonable value.
The practical consequence is that the contract remains the anchor even after it ends. That is a good reason to get the payment schedule right at the start rather than plan to litigate value later.
Security of Payment Is Usually Faster
For construction work, adjudication under the security of payment legislation is almost always the better first route: it is quick, it produces an enforceable determination, and it does not require you to prove market value from scratch. Quantum meruit is a court claim measured in years. See our note on adjudication and security of payment.
How to Never Need This Page Again
- No work before a signed scope and price — including "urgent" work for a good client.
- A written variation procedure, used every time, with an email trail confirming direction before you proceed.
- Progress claims tied to defined milestones, so a right to payment accrues as you go.
- Suspension and termination rights that let you stop work lawfully when payment stops.
- A retention of title clause and a PPSR registration for supplied goods.
Related Reading
See security of payment adjudication, our contract drafting service and construction debt recovery.
Frequently Asked Questions
What does quantum meruit mean?
Latin for "as much as he has deserved". It is a claim for the reasonable value of work done or goods supplied where there is no enforceable contract price covering that work — a restitutionary claim, not a claim for damages.
When can I claim quantum meruit instead of suing on the contract?
Broadly, where no contract was ever formed, where the contract is void or unenforceable, where you performed work outside the agreed scope at the other party's request, or where the other party repudiated and you accepted the termination. If there is a valid contract price for the work, you sue on the contract.
How is a quantum meruit amount calculated?
By reference to the fair and reasonable value of the benefit conferred — usually market rates for labour, plant and materials, supported by timesheets, dockets, variation requests, quotes and expert evidence. It is not simply your invoice or your desired margin.
Did Mann v Paterson change quantum meruit in building disputes?
Yes. In Mann v Paterson Constructions Pty Ltd [2019] HCA 32 the High Court held that where a builder accepts the principal's repudiation, it cannot recover quantum meruit for work for which a contractual right to payment had already accrued, and any quantum meruit award is generally capped by the contract rate. The practical effect is that the contract price now anchors most claims.
Can I claim quantum meruit for variations that were never signed?
Sometimes — but it is the hardest kind of claim to run. Most construction and services contracts require written direction before variation work proceeds, and security of payment regimes reward contemporaneous paperwork. Verbal instructions plus a hopeful final invoice is a poor position to litigate from.
Is quantum meruit the same as unjust enrichment?
Quantum meruit is one species of restitutionary claim within the broader unjust enrichment framework. The elements you must prove are a benefit conferred on the other party, at your expense, in circumstances where it would be unjust for them to keep it without paying.
Next Step
Chasing payment for work with no signed contract? Book a 15-minute call — a senior lawyer will tell you honestly whether the claim is worth running, and quote a fixed fee if it is.
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