How Do You Defend a Subby Security of Payment Claim for Unapproved Civil Works?

Q: What happens if I miss the 10-business-day deadline for a payment schedule?

Under the NSW SOP Act, failing to provide a payment schedule within 10 business days, or an earlier timeframe stated in the contract, typically triggers a severe consequence. A respondent becomes liable to pay the full claimed amount if they fail to provide a payment schedule within this strict window. Missing this deadline means the subcontractor can often pursue the unpaid amount as a statutory debt in a court of competent jurisdiction.

John Merlo

Jul 10

14 min read

Updated: Jul 10

Key Takeaways

Failing to serve a compliant payment schedule within 10 business days may trigger a statutory debt for the full amount claimed by the subcontractor, regardless of the work's quality.
The risk of a downstream adjudication outcome can often be mitigated by carefully challenging the formal validity and jurisdictional basis of the subcontractor's payment claim under section 13 of the Building and Construction Industry Security of Payment Act 1999 (NSW) (SOP Act).
Even if an adjudication application proceeds, civil contractors can explore strategic withdrawal mechanisms under section 17A of the SOP Act to facilitate negotiations and potentially avoid a binding determination that could trigger insolvency events.
Cross-claims and back-to-back contract limitations typically do not offer comprehensive protection against rapid adjudication; civil contractors must usually "pay now, argue later" while preserving their right to commence civil proceedings for final resolution.

You are waiting on the developer or Transport for NSW to approve a massive variation for unexpected earthworks, and your drainage subcontractor has just dropped a payment claim on your desk demanding their cut. The upstream principal is dragging their feet, but the statutory clock under the SOP Act has already started ticking against you. If you ignore the subcontractor's paperwork while you try to sort out the head contract, you risk walking straight into a rapid adjudication that may force you to fund the shortfall out of your own cash reserves.

The Subcontractor Variation Squeeze: Timeline and Immediate Actions

You are caught in the middle: the upstream principal has not approved your variation, but your earthworks subcontractor expects to be paid this week. The clock is running, and you need to decide right now whether to aggressively defend the claim or face a cash flow crisis. This section outlines the unforgiving procedural timeline you must manage today to prevent the subcontractor’s progress claim from becoming an undefended statutory debt.

Separating the security of payment dispute from final contractual entitlement

The rapid adjudication framework is designed to keep money moving down the contracting chain, but it operates independently of your ultimate contractual rights.

A determination under the SOP Act acts as an interim statutory payment mechanism rather than a final binding resolution of contractual variation entitlements.

This means the "pay now, argue later" system may force you to release funds to the subcontractor immediately, even if you are ultimately proven right about the variation's value. While managing security of payment legislation claims, it is critical to remember that an adjudicator's interim decision does not extinguish your right to claw back overpayments later in final civil proceedings. Practitioners frequently see civil contractors panic at a poor adjudication result, forgetting that a court of competent jurisdiction can ultimately reverse the cash flow in final civil proceedings if the variation is proven invalid under the contract — with section 32 of the SOP Act expressly preserving that right and empowering the court to order restitution of any amounts paid under the adjudication.

Calculating Your Strict Payment Schedule Deadline under Section 14 of the SOP Act

The most critical number in this entire process is 10 business days. Under Section 14 of the SOP Act— which sets the 10-business-day deadline for issuing a payment schedule—a respondent becomes liable to pay the full claimed amount if they fail to provide a payment schedule within 10 business days (or an earlier contractual timeframe) after receiving a payment claim.

This timeline is unforgiving. If your subcontract specifies a shorter response period—such as seven days—that earlier deadline applies. The NSW Government's published guidance on Security of Payment, available through the NSW Fair Trading and Service NSW web portals, reinforces that this strict procedural mechanism leaves no room for informal extensions while you wait for the head contract superintendent to issue a direction.

The Fatal Trap of Verbal Disputes Instead of Written Schedules

Expert insight: Many head contractors mistakenly rely on site meetings or angry emails to reject a subcontractor’s claim, assuming the dispute is understood by both parties. Under Section 15 of the SOP Act—which sets out the debt recovery consequences of non-compliance—if a respondent fails to issue a payment schedule and fails to pay, the claimant can recover the amount as a statutory debt in court. Once those debt recovery proceedings are commenced, section 15(4) of the SOP Act also prevents the respondent from bringing any cross-claim or raising any defence relating to matters arising under the construction contract, which removes any scope to argue the merits of the variation at that later stage. Failing to document your rejection in a formally compliant schedule is likely to convert a highly debatable variation into an immediate debt that may be exceptionally difficult to defend in summary proceedings.

If you have missed this window, seeking independent legal advice is critical — many civil contractors contact Merlo Law’s team directly to rapidly assess their exposure before summary judgment is entered.

This is one of the most common ways a defensible dispute turns into an indefensible debt. A site foreman or project manager tells the subcontractor's representative on-site, or in a phone call, that the claim is rejected because the variation hasn't been approved upstream — and everyone walks away assuming the matter is dealt with. It isn't. Section 14 of the SOP Act does not recognise a verbal rejection at all — a payment schedule must identify the payment claim and indicate the amount (if any) the respondent proposes to pay, along with the reasons for withholding any shortfall, and this content can only be conveyed through a document actually served on the claimant. Consequently, a verbal knockback, an angry text message, or an internal email that never reaches the claimant carries no statutory weight whatsoever. What typically happens next is the subcontractor waits out the 10 business days, and because no compliant schedule was served, they are entitled to treat the full claimed amount as a statutory debt — even where the underlying variation dispute might genuinely favour the head contractor on the merits.

By the time this gap is identified, the 10-business-day window has usually closed, leaving no capacity to remedy it and no defence against the resulting statutory debt. Contractors who are squeezed between an unresponsive principal and an impatient subcontractor need to treat every incoming payment claim as requiring a written schedule regardless of how informally the dispute is otherwise being managed on-site — the paperwork obligation runs on its own clock, independent of the commercial conversation.

Scrutinising the Downstream Payment Claim for Jurisdictional Defects

Before you start calculating set-offs and arguing over the scope of the subcontractor's extra work, you must first verify whether they even have the right to use the statutory rapid payment framework. Attacking the formal validity of the payment claim is a primary procedural mechanism and often your strongest defensive strategy. Identifying a jurisdictional defect early can stop the adjudication process entirely, giving you back control over the dispute timeline and your cash flow.

Validating the Construction Contract Framework

The first line of defence is checking whether your arrangement actually meets the statutory definition of a construction contract. If the subcontractor performed the work on a vague handshake agreement or the scope clearly falls outside the Act's coverage, they may not possess the right to enforce payment through this accelerated pathway.

An adjudication application in New South Wales relies fundamentally on the existence of a valid construction contract under the under the SOP Act.

Getting construction law advice on the fundamental construction contract framework can help you confirm whether the arrangement meets the required definition. If a valid contract does not exist, an adjudicator typically lacks the jurisdiction to make a binding determination, and any subsequent application may be dismissed.

Striking Out Claims Lacking SOP Act Section 13(2) Formalities

Even if the contract is legally valid, the document served by the subcontractor must satisfy rigid statutory criteria to trigger the rapid timeline. Under Section 13 of the SOP Act—which sets out the formal requirements a payment claim must meet—a party claiming entitlement to a progress payment under a construction contract may formally serve a payment claim on the liable party.

To be considered valid under section 13 of the SOP Act, this claim must specifically identify the construction work, state the claimed amount, and — for construction contracts entered into on or after 21 October 2019 — expressly state that it is made under the SOP Act. This endorsement requirement was introduced into the SOP Act by the Building and Construction Industry Security of Payment Amendment Act 2018 (NSW) and does not apply retrospectively to contracts executed before that commencement date. If the claim fails to meet these SOP Act section 13 formalities, it may be invalid entirely. If the paperwork is defective, commercial lawyer NSW will typically advise you to raise this jurisdictional defect in your payment schedule to strike out the subcontractor's claim before an adjudicator proceeds to value the work.

Assembling Your SOP Act Section 14 Payment Schedule Defences

If you determine that the subcontractor's claim is valid on its face, your only mechanism to contest the amount is a comprehensive and timely payment schedule. This is the moment where you must clearly detail every deduction, back-charge, and reason for withholding payment, because whatever you fail to include here cannot be raised later in an adjudication response. This section outlines how to structure your deductions so an adjudicator can see the evidence supporting your reduced assessment.

Deploying Back-to-Back Clause Limitations and Set-Offs

Head contractors often attempt to rely on back-to-back flow-down clauses, which are designed to align subcontract payments with head contract approvals. However, the enforceability of this clause depends on strict statutory constraints.

"Pay when paid" provisions in New South Wales construction contracts have no effect under section 12 of the SOP Act and cannot be enforced against a claimant seeking a progress payment.

Because these clauses are invalid, you generally cannot schedule an amount at zero simply because the principal has not yet approved the corresponding upstream variation. While back-to-back clauses can be highly effective for managing scope and standard of work, relying on them as a procedural mechanism to delay payment under the Act is likely to fail in adjudication. If you find yourself squeezed by these conflicting contractual timelines, seeking guidance from NSW building and construction lawyers may help you structure alternative, valid reasons for withholding payment.

Documenting Non-Conforming Work to Justify Scheduled Shortfalls

Warning: Setting off costs for defective or non-conforming civil works—such as poor compaction or drainage failures—requires robust, contemporaneous evidence. You cannot simply assert that the work was defective; you must include documentation like formal defect notices, photographic records, and superintendent directions within your SOP Act payment schedule. If you attempt to introduce this evidence later, an adjudicator is likely to reject the deduction as an afterthought — without contemporaneous records on file, your set-off is unlikely to survive scrutiny.

The "Pay Now, Argue Later" Constraint on Cross-Claims

The rapid adjudication framework imposes severe constraints on complex cross-claims, meaning that even a valid claim against a subcontractor may not provide an immediate defence against their progress claim. Section 32 of the SOP Act preserves your existing contractual and civil rights and confirms that nothing done under the adjudication process affects later civil proceedings arising under the construction contract, except that a court or tribunal hearing those proceedings must account for any amount already paid under the Act and may order restitution of that amount as it considers appropriate — this is the statutory footing for the "pay now, argue later" doctrine. If an adjudicator forces immediate payment despite your cross-claim, you must typically pay the determined amount first, but you retain the right to commence civil proceedings—and potentially leverage a Calderbank offer—to recover those funds when final contractual entitlements are assessed by a court.

Strategic Responses to an Adjudication Application under Section 17 of the SOP Act

When the subcontractor's adjudication application finally lands on your desk, the battle shifts from paperwork to high-stakes legal strategy. You must now determine if there is an opportunity to short-circuit the process through a negotiated withdrawal or if you need to prepare for a jurisdictional fight in the Supreme Court. This section outlines advanced tactical options to help you regain control of the dispute trajectory when a binding third-party determination is imminent.

Leveraging Withdrawal under Section 17A of the SOP Act to Force Negotiations

Under Section 17 of the SOP Act—which sets out when a subcontractor can file an adjudication application— a claimant is entitled to apply for adjudication if the respondent issues a payment schedule proposing to pay less than the amount claimed, fails to pay the whole or any part of a scheduled amount by its due date, or fails to provide a payment schedule at all and subsequently fails to pay the claimed amount by its due date — in which last circumstance the claimant must first serve a notice of intention to apply for adjudication (commonly referred to as a "second chance notice") on the respondent under section 17(1)(b) of the SOP Act before lodging the application. However, once this adjudication application under section 17 of the SOP Act is lodged, you may still possess procedural leverage. Introduced by the Building and Construction Industry Security of Payment Amendment Act 2018 (NSW), Section 17A of the SOP Act sets out a claimant's right to withdraw during an active adjudication.

Section 17A of the SOP Act allows a claimant to withdraw an adjudication application at any time before an adjudicator is appointed, or after appointment but before a determination is made, by serving written notice of the withdrawal on the respondent and on the authorised nominating authority or adjudicator. However, once an adjudicator has been appointed, that withdrawal does not take effect if any other party to the construction contract objects to it and the adjudicator considers it is in the interests of justice to uphold that objection — meaning the claimant does not hold an unconditional right to withdraw once the adjudication is underway.

If your adjudication response exposes a fatal jurisdictional flaw in their paperwork, the subcontractor may realise their claim is likely to fail. Deploying this exposure as a targeted dispute strategy, you can pressure the claimant to voluntarily withdraw their application before an adjudicator is appointed, or lodge a formal objection to any purported withdrawal after appointment so the adjudicator is compelled to determine the application on its merits, allowing both parties to return to the negotiating table without the immediate risk of a binding interim payment order. Note that the right to object under section 17A(2) of the SOP Act is not limited to the respondent — the legislation confers that right on any other party to the construction contract concerned, which may be relevant in multiparty project structures involving a principal, head contractor and subcontractor.

Escalation Risk: Preparing for Supreme Court Jurisdictional Challenges

Expert insight: An adverse adjudication determination may feel definitive, but it can sometimes be challenged if the adjudicator made a fundamental error of law. As a separate exposure channel, well-funded civil contractors frequently explore Supreme Court of New South Wales litigation to quash determinations based on jurisdictional errors—such as the adjudicator deciding a dispute where no valid construction contract existed. However, this escalation pathway can involve substantial legal costs, and courts are generally reluctant to interfere with the rapid adjudication framework unless the jurisdictional error is clear and material.

In practice, the decision to pursue this pathway usually turns on a fairly blunt cost-benefit calculation rather than the theoretical strength of the jurisdictional argument. Judicial review proceedings in the Supreme Court of New South Wales are not cheap, and by the time a contractor has briefed counsel and prepared the supporting material, the legal spend can quickly approach a meaningful proportion of the disputed sum — which makes this route difficult to justify unless the determination is large or the jurisdictional flaw is genuinely clear-cut, such as a construction contract that plainly did not exist or a claim served outside any arguable entitlement date — whether that is a reference date under a pre-21 October 2019 contract, or the last day of the relevant named month under a post-2019 contract.

For smaller or midsized determinations, most well-advised contractors find it commercially preferable to pay the determined amount, preserve the funds administratively, and pursue the true contractual value of the variation through final civil proceedings rather than through an urgent challenge to the adjudicator's jurisdiction. The Supreme Court route tends to be reserved for situations where the contractor expects to face the same jurisdictional issue repeatedly across a project — for example, a pattern of defective payment claims from the same subcontractor — where a successful challenge has value beyond the immediate dispute.

Conclusion

The "squeezed in the middle" scenario is one of the most perilous commercial positions a civil contractor can face. When an earthworks or drainage subcontractor initiates the rapid adjudication process for an unapproved variation, the downstream pressure can threaten your operating cash flow long before the upstream principal assesses the head contract claim. As outlined, ignoring the subcontractor's payment claim or relying on verbal rejections is not a valid strategy; failing to issue a compliant payment schedule within 10 business days may crystalise the claim into an immediate statutory debt, regardless of the ultimate contractual merits.

However, a well-prepared civil contractor retains significant defensive options. By meticulously challenging the jurisdictional validity of the downstream payment claim under section 13, detailing your set-offs with contemporaneous evidence in a timely payment schedule, and strategically leveraging withdrawal mechanisms under section 17A, you can often derail a weak application or force a negotiated settlement. Remember that the "pay now, argue later" framework is an interim cash flow measure, and it does not permanently extinguish your right to recover funds in final civil proceedings.

To protect your business from immediate cash flow shocks, your immediate next step should be auditing your standard payment schedule templates and internal site reporting procedures to ensure that every subcontractor progress claim is met with a robust, documented, and statutorily compliant response within the strict 10-business-day window. If a payment claim is already sitting on your desk, contact Merlo Law's construction team today — the earlier we review the claim, the more defensive options remain available within the statutory timeframe.

Being caught between an unresponsive principal and an impatient subcontractor is genuinely stressful, particularly when your own cash flow and reputation are on the line — but with the right procedural response, this is a manageable position, not a losing one.

FAQs

What happens if I miss the 10-business-day deadline for a payment schedule?

Under the NSW SOP Act, failing to provide a payment schedule within 10 business days (or an earlier timeframe stated in the contract) typically triggers a severe consequence. A respondent becomes liable to pay the full claimed amount if they fail to provide a payment schedule within this strict window. Missing this deadline means the subcontractor can often pursue the unpaid amount as a statutory debt in a court of competent jurisdiction.

Can I refuse to pay the subcontractor if the head contract variation isn't approved?

Generally, you cannot withhold payment solely because the upstream principal or Transport for NSW has not yet approved the corresponding head contract variation. "Pay when paid" clauses in New South Wales construction contracts have no effect under section 12 of the SOP Act and cannot be enforced against a subcontractor's progress payment claim. Attempting to use upstream delays as a procedural mechanism to deny a downstream payment claim is likely to fail in an adjudication.

Do I have to pay if the subcontractor's civil works are defective?

You may be able to deduct costs for non-conforming civil works, but this depends heavily on your supporting evidence. Setting off amounts for defective work requires you to include robust, contemporaneous documentation—such as formal defect notices—directly within your section 14 payment schedule. If you fail to substantiate these deductions at the time of scheduling, an adjudicator may reject the set-off entirely.

Can a subcontractor withdraw an adjudication application in NSW?

Yes, the Act provides a specific procedural mechanism for withdrawal. Section 17A of the NSW SOP Act allows a claimant to withdraw an adjudication application at any time before an adjudicator is appointed, and after appointment but before a determination is made — although once an adjudicator has been appointed, the withdrawal will not take effect if any other party to the construction contract objects and the adjudicator considers it is in the interests of justice to uphold that objection. Civil contractors can often leverage this rule to negotiate a withdrawal if they demonstrate that the subcontractor's application contains a fatal jurisdictional defect, or lodge an objection to prevent a late withdrawal that would deny them a determination in their favour.

Is an adjudicator's decision final and binding on my company?

An adjudication determination operates as an interim statutory payment mechanism rather than a final binding resolution of your ultimate contractual rights. While the Act generally requires you to "pay now," it also preserves your right to commence civil proceedings later to argue the true value of the works. If you are ultimately successful in court, you may recover any overpayments forced by the adjudication.

Can I challenge an adjudication determination in the Supreme Court?

You may seek judicial review to quash a determination, but only on very narrow grounds. Challenges in the Supreme Court of New South Wales typically focus on proving that the adjudicator committed a jurisdictional error, such as determining a dispute where no valid construction contract existed. Because this pathway can be exceptionally expensive, courts usually apply a high threshold before intervening in the rapid payment framework.

This guide is for informational purposes only and does not constitute legal advice. For advice tailored to your specific circumstances, please contact Merlo Law