Liquidated Damages in Australian Construction: How the Number Is Actually Calculated

It is the first week of August. The contracts administrator at a mid-sized Sydney builder opens the superintendent’s payment certificate and finds a line nobody on the project wanted to see: liquidated damages, 63 days at $5,500 a day, $346,500 set off against the claim.

She pulls the contract. Item 24 of the AS 4000 annexure says $5,500 per day. The project manager says the date is wrong, because a 10-day extension of time for late design information is still undetermined. Nobody can say, without a spreadsheet and an afternoon, what the number should be.

The liquidated damages clause is the one line that turns a programme slip into cash, and on most projects the inputs that drive it live in three different places.

What are liquidated damages in construction?

Liquidated damages (LDs) are a sum fixed in the contract that the contractor pays the principal for each day, or week, that the works run past the date for practical completion. The rate is meant to be a genuine pre-estimate of the principal’s loss, agreed in advance so the principal does not have to prove what the delay actually cost.[1]

Under AS 4000-1997, the rate is stated in Item 24 of Annexure Part A.[2] The date it runs from moves with every extension of time granted, which is why the LD bill and the EOT register are really one record. We cover the trigger itself in practical completion in construction.

Is a liquidated damages clause enforceable in Australia?

Usually, yes. A liquidated damages clause fails only if it is a penalty, and the High Court reshaped the doctrine in two decisions four years apart.

In Andrews v ANZ in 2012, the High Court held that the penalty doctrine is not limited to sums payable on breach of contract.[3] For construction, the point is that relabelling is unlikely to work: calling an LD a “reduction in the contract sum” does not change what it is.

“The question is one of substance rather than form.”

High Court of Australia, judgment summary, Andrews v Australia and New Zealand Banking Group Ltd [2012] HCA 30[3]

Four years later, Paciocco v ANZ tested late payment fees of $35 and $20 against evidence that the bank’s direct cost of a late payment was about $3.[4] The fees survived, because the bank could point to wider interests, such as loss provisioning, regulatory capital and collection costs, that the fees protected.

$35 vs $3

A late fee more than ten times the bank’s direct cost was still not a penalty, because it protected wider legitimate interests.

Paciocco v ANZ [2016] HCA 28

How do courts test liquidated damages now?

After Paciocco, mere disproportion to actual loss does not make a clause a penalty. The sum must be extravagant and unconscionable in amount, out of all proportion to the principal’s legitimate interests in timely completion, including the greatest loss that could flow from the delay, and the party alleging the penalty carries the onus of proving it.[2]

In practice, contractors attack the rate with industry benchmarks and with the principal’s own calculations, or the lack of any, to show nobody genuinely tried to quantify the loss when the contract was signed.[5] Courts start from freedom of contract, and the contractor carries the onus. In Growthbuilt v Modern Touch Marble & Granite [2021] NSWSC 290, a subcontractor on a $60,500 subcontract argued the head contractor could not have anticipated any loss, but did not discharge that onus, and the court enforced $3,500 a day for 122 days.[2]

$427,000

122 days at $3,500 per day, enforced against a subcontractor who argued the head contractor could not have anticipated any loss.

Growthbuilt v Modern Touch Marble & Granite [2021] NSWSC 290, via Bartier Perry

How is the liquidated damages rate actually calculated?

A defensible rate is a list of the principal’s real daily costs of not having the building, added up at tender and kept on file. Carter Newell’s checklist for principals runs to more than a dozen categories.[6] The main ones are below.

Keep the itemised calculation on file. It is the principal’s best evidence if the clause is ever challenged.[5]

Two traps catch principals. The first is double counting: if the building is held for rent, interest runs after completion anyway, so the loss is the rent plus only the extra finance cost. The second is copying last job’s rate, which weakens the principal’s evidence if the rate is challenged.

Worked example: a liquidated damages calculation from rate to bill

Assumptions: a developer in Western Sydney builds an $18 million medical and commercial building under AS 4000-1997, with LDs counted in calendar days and a special condition capping them at 5% of the contract sum. The building is pre-leased to a tenant on a net lease. These figures are illustrative.

Step 1: build the rate at tender.

The developer rounds this to $5,500 a day for the annexure and keeps the workpaper. The cap is 5% of $18,000,000, which is $900,000. At $5,500 a day the cap is reached on day 164 ($900,000 ÷ $5,500 = 163.6).

Step 2: count the days. The date for practical completion is 14 May. Practical completion is reached on 30 July, 77 days later. The superintendent has granted 14 days of EOT (9 for a latent condition, 5 for a variation), which moves the adjusted date to 28 May. Another 10 days for late design information are claimed but not determined.

The undetermined claim is worth $55,000 (10 × $5,500). Both outcomes sit well under the $900,000 cap. Had the job run 200 days late, uncapped LDs of $1,100,000 would have been cut to $900,000.

To run your own job, use Plexa’s free liquidated damages calculator. Enter the rate (per day or per week), the date for practical completion, the actual or forecast completion date, EOT days granted and still undetermined, any cap (percentage or fixed amount), and calendar or business days. It returns the exposure, a best and worst case range, and the working, as an indicative figure rather than legal advice.

How do extensions of time change the liquidated damages bill?

Every EOT day granted moves the date for practical completion out by a day and removes a day of LDs. EOT notice discipline is therefore an LD question, covered in extensions of time in Australian construction.

The principal also needs the EOT clause. Under the prevention principle, a principal cannot delay the contractor and then charge LDs for the late completion. If the contract has no way to extend time for principal-caused delay, time is “at large”, the LD clause cannot operate, and the principal is usually left to prove general damages.[7]

That is why EOT clauses cover principal-caused delay. In Peninsula Balmain v Abigroup (2002), the contractor had missed the notice requirements, yet the court held the extension still had to be considered honestly and fairly, where the contract gave the superintendent a power to extend time on its own initiative, which PwC’s analysis of prevention calls a significant extension of the principle.[7]

Do not treat this as a safety net. Principals are advised to add a separate power to extend time at any time, drafted as an absolute discretion that need not be exercised for the contractor’s benefit. Under a tightly drafted EOT clause, a contractor who fails to claim will generally be unable to rely on prevention to escape LDs, although one Northern Territory decision (Gaymark, 1999) went the other way.[7] The notice inside the window is still the only reliable protection.

[DIAGRAM] Type: Horizontal timeline with three markers and one shaded band Content: Marker 1 “Date for PC: 14 May”. Marker 2 “Adjusted date: 28 May (+14 days EOT granted)”. A hatched segment from 28 May to 7 June labelled “10 days claimed, undetermined: $55,000 swing”. Marker 3 “Actual PC: 30 July”. A shaded band from the adjusted date to actual PC labelled “LD days: 53 to 63 at $5,500”. A dashed horizontal line above the band labelled “Cap: $900,000 (day 164)”, well clear of the band. Alt text: Timeline showing how extensions of time move the date for practical completion and shrink the liquidated damages period, with the cap shown well above the accrued amount Caption: The LD bill is set by the gap between the adjusted date and actual practical completion. Every EOT day decided moves the left edge.

What happens when the annexure says nil, N/A or is left blank?

AS 4000-1997 puts the LD rate in Item 24 of Annexure Part A.[2] Unlike several other items in that annexure, Item 24 carries no “if nothing stated” fallback, so the standard itself does not say what a blank, “nil” or “N/A” means. AS 2124-1992 has separate annexure lines for the LD rate (clause 35.6) and the limit of LDs (clause 35.7), and in Silent Vector the court had to decide what “N/A” against both meant.[8] The cases do not line up neatly.

The Australian line, summarised in DLA Piper’s review of the cases, is that several appeal courts have held a nil or nominal rate does not, without clear words, exclude common law damages.[1] The position is not settled: WA authority has suggested “NIL” can exclude delay damages, and the AS 4000:2025 annexure note warns that “$Nil” or zero is likely to mean no damages at all.[8][9] A contractor who thinks “nil” means no delay liability may face the principal’s full proven loss instead.

The fix is words, not abbreviations. If no delay damages are intended, say so expressly. If the principal wants to keep general damages, say that LDs do not apply and that the right to general damages for delay is reserved.[6]

How do caps on liquidated damages work?

The unamended AS 4000-1997 annexure has no item for capping LDs, so a cap arrives by special condition. AS 2124-1992 has a “Limit of Liquidated Damages” line, which only helps if it is filled in properly.[8] Contractors typically ask for 5% to 10% of the contract sum, roughly their margin, and Carter Newell warns principals not to set it so low that it stops working as a disincentive to delay.[6]

5% to 10%

The LD cap contractors typically ask for, expressed as a share of the contract sum.

Carter Newell, 2024

Check what happens at the cap. If LDs are not stated to be the sole remedy for delay, the principal may argue it can claim general damages beyond it, and clear words decide that question.[7]

Liquidated damages or general damages: what is the difference?

Where a genuine LD rate applies, it normally fixes the damages for late completion. The clear-words rule bites hardest where the rate is nil or nominal, or where the principal wants to recover beyond a cap.[1][7] Where LDs are deducted from payments or called from security, the contract’s set-off and security provisions apply, which we cover in construction retention and in our upcoming post on bank guarantees and cash retention.

What good looks like

• The rate has a dated, itemised workpaper behind it

• Nil, N/A, the cap and the sole-remedy position are spelled out in words

• Every EOT claim, granted, refused or pending, carries its LD value in dollars

• LD exposure is forecast from the live programme, not found on a payment certificate

The Australian context

Most commercial work runs on AS 4000-1997, AS 2124-1992 or AS 4902, usually amended, and some projects now use AS 4000:2025, where the LD rate sits at Item 28 and the annexure itself warns that “$Nil” or zero is likely to mean no liquidated or general damages.[9] Item numbers and wording differ between editions, so read the executed annexure.

Residential contracts are their own world, and small or nominal daily rates are common. Carbone v Fowler Homes, decided on a standard form residential building contract, shows the NSW Court of Appeal will not treat $1 a day as a cap on everything the owner can claim.[1] The cases above also come from WA and NSW, so check the position in your state.

LDs stop at practical completion (or earlier termination). Defects after that, and the security held against them, belong to the defects liability period, covered in our upcoming post on the defects liability period.

This is general information, not legal advice; the executed contract, with every amendment, decides the answer.

Where Plexa fits

The arithmetic is simple. The inputs drift apart: the rate sits in the contract, the adjusted date in the EOT register, the forecast completion in the programme.

In Plexa, the Correspondence module automatically generates the EOT register, with every claim version controlled and tracked to closure. The Program module tracks milestones and forecasts completion. The Head Contract module tracks approved and pending claims, variations and retention, and cost-to-complete forecasting shows financial exposure as it moves. The site diary holds the daily record an EOT claim leans on.

Back in that August payment certificate, the CA does not need an afternoon. The pending 10-day claim is on the register with its date, the programme shows why it mattered, and the $55,000 that hangs on it is a number the whole team already knew.

Frequently asked questions

Are liquidated damages enforceable in Australia? Yes, unless they are a penalty. After Paciocco, the party alleging a penalty must show the rate is extravagant and unconscionable, out of all proportion to the greatest loss that could flow from the delay.[2][4]

What does “nil” or “N/A” for liquidated damages mean? It depends on the contract. Several Australian appeal courts have held that nil or nominal rates do not exclude general damages without clear words, and “N/A” has been read as switching the LD clause off, leaving general damages available. The position is not settled, and the AS 4000:2025 annexure warns that “$Nil” or zero is likely to mean no damages at all.[1][8][9]

Can a principal charge liquidated damages if it caused the delay? Not for that delay. Under the prevention principle, principal-caused delay must be dealt with through an EOT. If the contract cannot extend time for it, the LD clause may not operate at all.[7]

Related reading

The time side of every LD bill is in extensions of time in Australian construction, and the date LDs run to is in practical completion in construction. For how contract forms allocate risk more broadly, see types of construction contracts.

If you want to see how EOTs, programme forecasts and head contract claims sit in one record on a live project, book a 30-minute demo with the Plexa team.