Variation claims in Australia: AS 4000, AS 2124 and the 2026 changes

This page is the orientation for the Australian variations layer of the library. It sits under the general variations guide, which states the doctrine without a jurisdiction. Each section below points to the Australian page that carries the detail, and every page in this layer states where its evidence comes from, including what could not be read.

The short answer

1 · A written-variation clause does not stop an oral variation. Australian law has never adopted the rule in Rock Advertising Ltd v MWB Business Exchange Centres Ltd [2018] UKSC 24, under which a no-oral-modification clause is enforced as written. The High Court's starting point is Liebe v Molloy [1906] HCA 67: a clause requiring extras to be ordered in writing does not exclude recovery on a separate express or implied promise to pay, but that promise must be proved as a fact; the owner's knowledge that the work was being done is not enough. The Court stated the principle and sent the facts back to the umpire. The Federal Court applied the same approach to a no-oral-modification clause in GEC Marconi [2003] FCA 50, while treating the clause as weighty evidence against a claimed oral variation. In New South Wales the Court of Appeal has noticed Rock Advertising without adopting it. In Sara Stockham v WLD Practice Holdings [2021] NSWCA 51 at [15], Leeming JA said it "has repeatedly been said not to reflect the position in Australia". No appellate decision deciding the point squarely was located, and no High Court decision on it was located.

2 · But under AS 4000 an oral instruction is not a variation direction. AS 4000 cl 36.1 provides that the Contractor shall not vary the work except as directed in writing, and gives the Superintendent power to direct a variation before the Date of Practical Completion. That wording appears in two independent public copies of the form family: an amended AS 4000-1997 and the amended AS 4902-2000 set out in Kaloriziko. So the 2025 edition did not create the written-direction rule; firm summaries report that it restated it (HWL Ebsworth: shortened and clarified it). (Inference, from two amended copies; no licensed copy of AS 4000:2025 was read.) The consequence matters more than the rule. A contractor who built on an oral instruction has not lost the claim. But it has lost the contract's pricing machinery, and it now has to prove an agreement or an estoppel with the Principal, not an instruction from the Superintendent's site team. The written instruction page works through that, the Principal-direct-instruction trap, email directions under the 2025 edition, and why the window for a direction can close before the Practical Completion certificate issues.

3 · Approving a "variation" does not make it one. Kaloriziko [2025] NSWCA 259 is the most useful recent Australian variation decision, and it is widely misreported. It was an AS 4902-2000-based design and construct contract, not AS 4000. The developer had approved, but not paid, a consultancy-fee claim that was work already within the contract. The Court of Appeal held that "the pricing of a non-variation does not convert it to a variation" and that, because payments other than final payment were "on account only", approval did not bind the developer; as the headnote puts it, approval was no more than an implied admission. The developer was entitled to a credit of $133,175. That is the only part of the $3.24 million reduction on appeal that concerned a variation. The rest was $210,000 of liquidated damages and a $2.9 million credit for a settlement deed. Five other "approved" items were also held not to be variations. The builder kept that money anyway, because the contract made those items separately payable. The lesson is narrow and important: a variation register full of approvals is not a register of variations.

4 · Pricing runs down a ladder the Superintendent climbs. In the AS 4000 family, cl 36.4 requires the Superintendent to price each variation using an order of precedence (the amended AS 4000-1997 copy read adds "as soon as possible"): prior agreement, then applicable rates or prices in the Contract, then rates in a priced bill or schedule even though it is not a Contract document, then, as firm summaries report, reasonable rates. The reasonable-rates limb is not in the amended 1997 copy read, and its margin wording is reported inconsistently; see the valuation page. In the 1997 numbering, confirmed from a public amended copy, cl 36.2 is the proposed-variation procedure, not the pricing clause, and the Contractor's response to a proposed variation includes time-related costs. That places delay cost inside the variation price where the procedure is used. The valuation page sets out the ladder, the reported omission and deduction rules, and a "10% of the net omission" rule that circulates in commentary and could not be found in any source read.

5 · The form decides what gets deemed. Australian law has no doctrine called constructive change. What it has is contractual deeming. AS 4000 has long routed latent conditions into the variation machinery (cl 25.3 prices a latent condition under cl 36.4 "as a Variation" in the 1997 edition as reproduced in a public copy; whether the 2025 edition keeps that is not confirmed by any summary read [EDITION ALERT]). Firm summaries report that the 2025 edition adds out-of-tolerance bill of quantities items, provisional sums and discrepancy directions. AS 2124-1992 treats the same facts differently. The deemed variations page compares the two forms and explains when the claim is really one for breach damages, with a different measure.

Where Storia fits

Every question on this page is answered from the project record: who gave the instruction, what it said, when, whether it came before Practical Completion, and whether the work was already in scope. Storia turns drawings, RFIs, schedules, correspondence and field reports into one source-linked project record, so each answer points to the document it came from. It builds that narrative as the work happens, so a variation account can be defended on the evidence rather than on a folder of approvals.

Victoria is now different

On 15 April 2026 Victoria repealed ss 10A–10B of the Building and Construction Industry Security of Payment Act 2002. Those sections had made disputed variations "claimable" in adjudication only on smaller contracts, or where the contract had no dispute-resolution method. They also excluded, unless they were claimable variations, compensation for events (latent conditions, time-related costs, regulatory change), and damages claims. Read from the pre-reform authorised version, the second class of claimable variation covered a disputed variation only where the contract sum was $5 million or less, or the contract had no dispute-resolution method. Once disputed variations passed 10% of the contract sum, that threshold fell to $150,000. No other Australian security-of-payment Act located has such a gateway (Jones Day's 2020 national survey describes Victoria's as unique).

Three changes now matter to anyone running a Victorian variation account:

• The gateway is gone. A disputed variation can be claimed and adjudicated like any other amount. Under transitional s 54(2), payment claims served, and adjudication applications made but not determined, before 15 April 2026 keep the old Part 3 rules.
• The payment schedule now carries the respondent's whole case. Before the reform, s 21(2B) let a respondent raise new reasons in its adjudication response, with a two-business-day reply for the claimant. The amended s 21(2)(d) bars reasons that were not in the payment schedule.
• s 13A lets an adjudicator, court, arbitrator or expert declare a notice-based time bar unfair for a particular entitlement. The ground is that compliance was not reasonably possible or would be unreasonably onerous, and the onus is on the party alleging it. Whether s 13A reaches a clause that makes a variation depend on a written direction, rather than on the contractor's notice, is undecided. No decision applying s 13A, or the comparable Western Australian s 16, was located on AustLII to about June 2026.

The Victoria page orients the change, and the adjudication page reads the provisions from the authorised Act. Queensland's Building Industry Fairness (Security of Payment) Act 2017 has no equivalent of s 13A. Security of payment generally, state by state, is covered on the Australian security of payment page.

The forms in use, and why it matters which one you have

(Comparison. Sources: the amended public copies named in the evidence notes and firm summaries; no licensed copy of any of the three standards was read. Almost every Australian contract amends these forms, so check your special conditions before relying on any row.)

Carrying habits between forms loses claims. A contractor used to AS 2124, where site directions are often oral and the risk sits in the cl 46.1 notice, can walk onto an AS 4000 job and build a variation no one ever directed. An AS 4000:2025 head contract over a subcontract on older or bespoke conditions can leave the subcontractor on different notice and direction rules from the head contractor, unless the back-to-back drafting deals with it. (Opinion.)

Where Australian variation claims actually die

1. The direction. No written direction from the Superintendent before Practical Completion, and no provable agreement with the Principal to fill the gap.
2. Scope. The work was within the contract all along. Kaloriziko is the reminder that approval does not change that, and that "on account" payment language lets the Principal reopen it.
3. Notice. A missed cl 46.1 notice under AS 2124, or a claims-notification clause under AS 4000. Outside Victoria and Western Australia (WA contracts from 1 August 2022) no statutory route to declare the bar unfair was located. Inside them, no decision applying the route was located.
4. Quantum. A global claim that fails, fails entirely: Mainteck Services v Stein Heurtey [2014] NSWCA 184 at [182]. And no Australian decision endorsing an overhead formula was located.
5. The seam with delay. Time-related cost included in a cl 36.2 proposed-variation price cannot be claimed again as prolongation. Whether cost left out of an agreed price can be recovered separately depends on the contract's words. Chengcheng v Mansfield [2018] NSWCA 244 allowed a separate liquidated delay-losses claim alongside agreed and paid variations on a bespoke contract. (Opinion, and one decision on a non-standard form.) See prolongation and delay costs in Australia.

What to do about it

(Opinion, offered as working practice rather than as authority.)

1. Know your form and your amendments before the first site instruction: which clause, who directs, and whether the direction must be written.
2. Ask for the written direction the same day an instruction is given orally, and record who gave the instruction and when. The templates include a request for a written direction.
3. Serve the notices separately: the variation, the extension of time, and the cost claim each have their own clock. See notice and time bars in Australia.
4. Keep the scope trail, not just the approvals. The question after Kaloriziko is whether the work was outside the contract, and the answer is in the documents, not the approval.
5. In Victoria, put the whole case in the payment schedule if you are the respondent. If you are the claimant, plan the payment claim around the variation account you can now adjudicate.

About this material Library content is general information about construction claim practice, not legal advice. Entitlement, deadlines and procedure are governed by your own contract and by the law of the place the work is performed. Reviewed September 26, 2026 · Report a correction