If you’ve ever sat down with a contractor’s payment claim and wondered where to start, you’re not alone. the payment claim on the a major NSW road upgrade project landed with dozens of line items across BOQ quantities, rate disputes, variation claims, and subcontractor substantiation requests. Here’s how we worked through it — clause by clause — and why that approach is the only one that holds up.
The Problem With Vague Payment Responses
Most payment schedule disputes don’t start with fraud or bad faith. They start with vague responses.
A comment like “this item is under review” or “quantity disputed” gives you nothing to defend. When the contractor lodges an adjudication claim under SOPA, the adjudicator looks at your payment schedule first. If your reasons aren’t specific, clause-referenced, and tied to the actual contract, you’re in trouble before you’ve started.
The discipline of writing a proper payment schedule is the same discipline that protects you in a dispute. The two are inseparable.
The Framework: Every Comment Needs a Clause
Before touching a single line item, establish this rule: every rejection, reduction, or reservation must cite the contract clause that authorises it.
Not “insufficient evidence.” Cl.68.3 — substantiation required before assessment can be completed.
Not “rate seems high.” Cl.47.1 — rate not considered reasonable for the work described.
Not “this variation isn’t agreed.” Cl.47.10 — no adjustment to the Contract Price until the variation has been agreed or assessed under Cl.47.
This isn’t bureaucratic box-ticking. These clauses are your legal authority to withhold payment. Without them, your schedule is just opinion.
What We Actually Found in the payment claim
Working through dozens of line items on the payment claim, the claims broke into clear categories — and each category had a standard clause-referenced response.
Category 1: BOQ Quantity Disputes (Cl.59.1.3, Cl.68.3)
Several items claimed quantities that didn’t match our own measurements. Under Cl.59.1.3, payment is based on the quantity of work actually carried out, assessed using the rates in the Contract. Where we disputed the quantity, we noted our assessment of the correct quantity and the basis for it. Where we didn’t yet have survey data to confirm, we applied Cl.68.3 — payment on account only, pending receipt of survey or quantity reconciliation.
The key discipline: never leave a quantity dispute blank. Either assess it at your quantity, or explicitly flag what substantiation you need to complete the assessment.
Category 2: Rate Items — Tip Dockets Required (Cl.68.3)
Disposal items were claimed without supporting tip dockets. Under Cl.68.3, the contractor must provide documents reasonably required to substantiate amounts claimed. Tip dockets are standard substantiation for disposal. Response: assessment deferred pending receipt of dockets. No dockets, no payment.
Category 3: Variations — No Additional Information (Cl.47.10, Cl.68.3)
A number of variation line items were claimed without any supporting cost breakdown. Under Cl.47.10, no adjustment to the Contract Price occurs until the variation has been agreed or assessed. Under Cl.68.3, the contractor must substantiate the amounts claimed. Response: no assessment possible pending receipt of cost breakdown with labour hours, materials, and margin.
Category 4: Specific Rejection — Variation A (Cl.48.1)
Variation A was claimed as a variation. The problem: no written Variation instruction had been issued under Cl.48.1 before the work commenced. Cl.48.1 is unambiguous — a contractor is not entitled to additional payment for work carried out without a written instruction from the Principal’s Authorised Person. The claim was rejected on this basis, with the clause cited in full.
This is one of the most important protections in GC21. If a contractor does work without a written instruction and then claims it as a variation, Cl.48.1 is your shield. Use it.
Category 5: Concurrent Delay Reservation — Variation B (Cl.50.6)
Variation B involved a delay cost element. We assessed the variation on its merits but applied a concurrent delay reservation under Cl.50.6. Where the project has concurrent delays — some Principal-caused, some contractor-caused — a contractor is not entitled to delay costs for a period where its own concurrent delays would have caused the same loss. The reservation was noted in the payment schedule to preserve the position.
Category 6: Unreasonable Rate — Variation C (Cl.47.1)
Variation C included a rate we assessed as unreasonable for the work described. Cl.47.1 requires that varied work be valued at reasonable rates. Where a claimed rate is excessive, you’re entitled to substitute a rate you consider reasonable and explain your basis. We did exactly that, noting the comparable market rate and the reference we used.
Category 7: Duplication — Variation D, Variation E (costs captured elsewhere)
Two items were rejected on the basis that the costs were already captured in other variation codes. This happens frequently in complex projects where variations accumulate over time. The risk is double-paying the same cost under two different variation numbers. The response is straightforward: reject the duplicate, identify the variation code where the cost is already included.
The Structure That Makes It Defensible
The payment schedule that survives scrutiny has a consistent structure for every line item:
- The item as claimed — what the contractor said they’re owed
- the Principal’s assessed amount — what you’re paying
- The reason — clause-referenced, specific, tied to the actual facts
If the assessed amount matches the claimed amount, say so. If it doesn’t, your reason needs to be specific enough that the contractor knows exactly what they need to do to get paid — either provide the missing substantiation or challenge your assessment in adjudication.
Ambiguity doesn’t protect you. It just delays the inevitable.
The Cl.68.3 Clock
One thing contract administrators sometimes miss: Cl.68.3 creates a clock, not a permanent excuse to withhold payment.
When you withhold payment pending substantiation, you’re creating an obligation on the contractor to provide that information — and an implicit obligation on yourself to assess it promptly once they do. If the contractor provides the tip dockets, the quantity survey, or the cost breakdown, you need to reassess. Sitting on their response and continuing to withhold indefinitely is not a strategy; it’s an adjudication waiting to happen.
Set a clear deadline for substantiation in your response. “Assessment deferred pending receipt of tip dockets. If dockets are not provided within 5 Business Days, the item will be excluded from this claim period.”
That language is both fair and enforceable.
The Bigger Picture
Forty-six line items sounds like a lot. In reality, most of them fell into the same five or six categories. Once you have your standard clause-referenced responses for each category, processing a large payment claim becomes a pattern-matching exercise rather than a bespoke analysis for each line.
The investment is in building that reference set the first time. Once it exists, consistency is automatic — and consistency is exactly what you need when the contractor’s lawyers are reviewing your payment schedule.
On the payment claim, every rejection had a clause. Every reduction had a reason. Every deferral had a specific condition for completion. That discipline doesn’t just protect the current claim — it trains the contractor’s team about what they need to provide going forward.
The best payment schedule is the one that produces better claims next month.
If You’re the Contractor: How to Claim So You Actually Get Paid
Everything above is written from the Principal’s perspective. But the same clause knowledge that helps a Principal write a tight payment schedule tells contractors exactly what they need to include to get paid without a fight.
Front-load your substantiation. Don’t submit a claim and wait for the Principal to ask for evidence. Attach tip dockets to disposal items. Include a cost breakdown — labour hours, materials, margin — with every variation claim. Provide quantity calculations with survey references. The Principal’s legitimate reasons to withhold under Cl.68.3 disappear when the substantiation is already in the claim package.
Chase every written instruction before you start work. The Cl.48.1 rejection is one of the cleanest tools a Principal has — and the easiest for contractors to avoid. If you’re doing work that you believe is a variation, get written confirmation of the instruction before you move a machine. An email acknowledgment, a site instruction, a formal Cl.48 direction — any of these works. Work done without a written instruction is work done at your risk.
Use SOPA when the schedule is deficient. Under the Security of Payment Act, a payment schedule that doesn’t respond to a specific claimed amount with a specific reason is treated as a scheduled amount of nil — which triggers the contractor’s right to apply for adjudication for the full claimed amount. If the Principal responds to your claim with vague comments like “under review” or “disputed” without clause references and amounts, that’s not a complying payment schedule. Know the difference, and use it.
The Cl.68.3 clock runs against the Principal too. When you provide the substantiation the Principal asked for, they’re on the clock. If they withhold payment and sit on your response without reassessing, they’re accumulating adjudication exposure. Send the substantiation formally — with a covering letter, by email on record — and note the date. If 10 business days pass without a revised schedule, consider your options.
Protect your rate arguments under Cl.47.1. If your variation rates are being challenged as unreasonable, you need to show your workings. Market rate comparisons, subcontractor quotes, historical project data — whatever establishes that your rate reflects actual cost plus reasonable margin. A bare rate without justification is easy to reject. A rate with a quote attached and a methodology note is much harder.
The contract works the same way regardless of which side of the table you’re on. The difference is who does the homework first.
This post is based on real contract administration work on an active NSW infrastructure project. Contract clauses referenced are from GC21 Edition 2.