Set-Off and Back-Charges: Responding Line by Line, Not Emotionally

Somewhere near the end of most difficult projects, a payment schedule or certificate arrives carrying a wall of deductions: defect rectification by others, supervision costs, delay set-offs, "contra charges" with round numbers and one-line descriptions. The instinctive response is anger and a letter that says, in effect, we reject these outrageous deductions in their entirety. That response feels strong and achieves nothing. Deductions are defeated line by line, category by category, document by document — and the party that brings forensic discipline to the exercise usually ends up with the money.

First: does the deduction have a legal home?

Set-off is not a mood; it is a right that needs a source. Before engaging any number, ask where each deduction's entitlement comes from: an express contractual set-off clause (and its preconditions — notice, a superintendent's assessment, amounts "due and payable" versus merely claimed); the certification machinery (a superintendent valuing defective work downward is doing something different from a principal deducting its own claim); or general-law rights, which many contracts expressly exclude or confine. Amended subcontracts often grant the head contractor breathtakingly wide set-off rights — but wide is not unlimited, and preconditions are enforced as written.

Two statutory constraints sharpen the analysis on progress payments. Under security of payment legislation, deductions must appear as reasons in the payment schedule, on time — in NSW, reasons not in the schedule cannot be raised at adjudication (s 20(2B)), and the same lock-in now applies in Victoria's reformed regime. A respondent that papers a certificate with vague deductions has not preserved leverage; it has handed the claimant a map of an under-prepared case.

The six-category taxonomy

Every deduction belongs to one of six categories, and each category demands a different response:

1. Valuation — "the work is worth less than claimed" (measure, rates, percentage complete). Answer with: the contract structure, survey data, prior certified positions. The question: what changed since last month's certificate?
2. Entitlement — "no contractual basis for the claimed item". Answer with: directions, scope analysis, approval trails — the variations discipline from our companion guide.
3. Evidence — "not substantiated". Answer with: the substantiation, and a demand for particulars of what specifically is said to be missing. "Not substantiated" against an itemised claim with attachments is a non-reason, and adjudicators treat it accordingly.
4. Set-off / back-charge proper — defects, completion by others, delay damages, third-party costs. The contested heartland. Demand for each: the contractual source of the right; compliance with its preconditions (was a rectification notice given? was the contractor afforded its right to rectify before others were engaged?); proof the cost was incurred (invoices, not estimates); causation linking the cost to the alleged breach; and reasonableness of quantum. A back-charge for rectification by others, where the subcontractor was never given the contractual opportunity to rectify, fails at the second hurdle regardless of the defect's reality.
5. Administrative — duplicates, wrong-period items, arithmetic. Answer with: a reconciliation. These are the cheap wins that also establish whose spreadsheet the tribunal should trust.
6. Strategic / machinery — retention, security, conditions precedent invoked. Answer with: the clause analysis — and note the release rights now hardening in several states.

The categorisation is not bureaucracy. It converts an emotional confrontation into a tractable worklist, exposes which deductions are real (some usually are — concede those fast and gain credibility), and pre-builds the adjudication application or defence.

The escalation pathway

With the taxonomy done, escalate deliberately rather than reactively: a reconciliation meeting armed with the line-by-line analysis (many deduction walls halve in the first meeting once particulars are demanded); a formal commercial letter recording the unresolved categories and the evidence gaps on the other side; a negotiation package that prices the realistic outcome; and only then adjudication or the contractual dispute process, with the application largely pre-written by the work above. For claimants under SOPA, remember the respondent's schedule reasons are locked — every vague deduction in the schedule is a structural weakness in their adjudication response.

The same discipline serves the deducting party in reverse. Back-charges that survive scrutiny are contemporaneous (raised when the cost was incurred, not aggregated at final account), sourced (clause identified, preconditions met, rectification opportunity given), evidenced (actual invoices) and proportionate. A principal or head contractor that runs its deductions this way converts set-off from a negotiation bluff into recoverable money.

What this means in practice

1. Never respond globally. "All deductions rejected" concedes the framing and preserves nothing. Categorise within 48 hours, respond line by line, concede the real ones early.
2. Demand particulars as a standing first move. Source clause, precondition compliance, cost evidence, causation, quantum basis — five questions per back-charge, in writing. Most deduction walls are not built to survive the questionnaire.
3. Protect the rectification right. For contractors: a back-charge for others' rectification where you were never given the chance to rectify is usually beatable — say so with the clause. For principals: give the notice and the opportunity, on the record, before engaging others.
4. Mind the SOPA clock while you analyse. A deduction wall in a payment schedule may need an adjudication application within 10 business days. Run the taxonomy and the deadline diary in parallel — the analysis is worthless if the window closes.
5. Keep the certified history. Month-on-month certificate movements are the quiet evidence in valuation disputes: work certified at 90% for three months cannot quietly become 60% because relations soured. Track it.

Key takeaways

• Every deduction needs a legal home — an identified clause with its preconditions met — before its number deserves engagement.
• Categorise all deductions into the six-type taxonomy (valuation, entitlement, evidence, set-off, administrative, machinery) and answer each type on its own terms.
• Back-charges fail most often on preconditions: no rectification opportunity, no contemporaneous notice, estimated rather than incurred costs.
• SOPA locks respondents to their schedule reasons — vague deductions are leverage for the claimant, not protection for the respondent.
• Escalate deliberately: reconcile, correspond, package, then adjudicate — with the application pre-built by the line-by-line work.

This article is general information only and is not legal advice. For advice on a specific contract or dispute, seek legal counsel or contact Sumit Consulting for commercial and claims advisory support.