Liquidated damages are one of the most misunderstood clauses in any construction contract — and one of the most expensive to ignore. Whether you call them LADs (Liquidated and Ascertained Damages) in the UK or simply Liquidated Damages (LDs) in the US, the principle is the same: if you finish late, the client deducts a pre-agreed sum for every day or week of delay. Here's what you need to know before you sign.
Liquidated damages are a contractual mechanism that fixes the financial consequences of late completion in advance. Instead of the client having to prove their actual loss — which is often difficult and expensive — the parties agree upfront that a set rate will apply for every day or week the contractor finishes late.
The term Liquidated and Ascertained Damages (LADs) is used in UK construction contracts — JCT, NEC and bespoke forms. In the US, the same mechanism is typically called Liquidated Damages (LDs) and appears in AIA contracts, GMP agreements, and owner-drafted forms. The word "liquidated" means "calculated in advance" — it does not mean the damages are necessarily fair or proportionate.
LADs and LDs are not penalties — they are a genuine pre-estimate of the client's loss. Courts will generally enforce them unless they are found to be "extravagant and unconscionable." Rates of £5,000–£15,000 per week on subcontracts are routinely upheld.
The mechanism is straightforward. The contract specifies a completion date. If you fail to achieve that date — for reasons that are your fault — the client is entitled to deduct the LAD/LD rate from money owed to you, starting from the completion date and running until you achieve practical completion (UK) or substantial completion (US).
Critically, most contracts do not require the client to give advance notice before deducting. They simply withhold the sum from the next payment. By the time you realise what has happened, several weeks of deductions may have already been taken.
In JCT contracts, LADs are stated in the Contract Particulars at the front of the document. They apply to the Main Contract. Subcontracts under JCT typically flow down the same LAD rate — often without a proportionate reduction — meaning a subcontractor can carry the full main contract LAD exposure even though they represent a fraction of the overall scope.
Under NEC4 contracts, the equivalent mechanism is called Delay Damages and appears in the Contract Data. The principle is identical but the process differs — the Project Manager must certify the completion date and formally notify the delay before deductions can be made, which provides slightly more process protection for the contractor.
Many contracts include sectional completion dates — separate deadlines for different phases or areas of the works. Each section often carries its own LAD/LD rate. This means that even if you complete the overall project on time, you can face deductions for any section that ran late.
On a hospital refurbishment with three ward phases, for example, it's entirely possible to complete Wards A and B on time but face four weeks of LADs on Ward C — at the full contract LAD rate — despite overall practical completion being achieved on schedule.
Does the LAD/LD rate apply to the whole contract or to each section independently? Does the contract cap total LAD deductions? Is there a mechanism to recover LADs once practical completion is achieved?
Extensions of Time (EoT) — called time extensions or change orders in the US — are the mechanism that adjusts the completion date when delay is caused by events that are not the contractor's fault. Relevant events typically include: employer-caused delays, late information, changes to the scope, exceptionally adverse weather, and force majeure events.
The key point is that EoT provisions are not automatic. In JCT contracts, you must give notice of delay — typically within a specified period of becoming aware — and formally apply for an extension. Failure to give notice on time can bar your claim entirely, regardless of whether the delay was legitimately caused by the client.
Under most JCT and NEC contracts, you must give written notice of a delaying event promptly — typically within 8 weeks of becoming aware (NEC) or "forthwith" (JCT). Under AIA contracts, notice is typically required within 21 days. Missing the notice period can extinguish your right to a time extension entirely.
The LAD rate is stated in the contract — you cannot negotiate it at tender stage in most cases. What you can do is price the risk of delay into your bid through programme contingency, programme management overhead, and an honest assessment of whether the stated programme is achievable.
| Scenario | Risk Level | Pricing Response |
|---|---|---|
| Realistic programme, standard JCT/AIA terms, no amendments | LOW–MED | Standard prelims, programme float built in |
| Tight programme, live environment, restricted hours | MED | Extended prelims, programme risk allowance 2–3% |
| Tight programme, missing information, incomplete design | HIGH | Substantial programme risk premium, qualify programme heavily |
| High LAD rate (over 2% of contract value per week), no cap | HIGH | Qualify: propose cap at 10% of contract value |
| Sectional completions with independent LAD rates per section | HIGH | Price each section independently, flag in qualifications |
You cannot usually remove LAD clauses from a contract, but you can and should push back on rates that are disproportionate to your scope of work. A subcontractor carrying the full main contract LAD rate is a common and legitimate negotiating point — particularly where your trade represents 10–15% of the overall contract value but you carry 100% of the LAD exposure if your work is on the critical path.
Reasonable pushbacks include: proposing a cap on total LAD deductions (typically 10% of subcontract value), proposing a LAD rate proportionate to your subcontract value, and seeking back-to-back LAD provisions that flow down only in the event that the main contractor has been assessed LADs attributable to your delay.
"A subcontractor carrying uncapped LADs at the main contract rate is carrying a risk that could eliminate their entire margin on a single project. Always read the LAD provisions — and always qualify."
A genuine liquidated damages clause is enforceable. A penalty clause — one where the sum is grossly disproportionate to the actual loss — is not. The legal test in the UK (post-Cavendish Square v Makdessi [2015]) and the US (Restatement (Second) of Contracts) is whether the pre-estimate was a genuine attempt to quantify likely loss at the time the contract was entered into.
In practice, challenging a LAD clause as a penalty is expensive and uncertain. It's not a defence strategy — it's a last resort. The better approach is to identify and qualify high LAD risk before you sign, not after you've overrun.
TenderScope reviews your contract conditions — LAD rates, retention, payment terms, termination clauses and more — and flags every onerous provision in plain language. First report free.
Get Your Free Contract Analysis →| What to Check | What Good Looks Like | Red Flags |
|---|---|---|
| LAD/LD rate | Proportionate to delay loss, typically 0.5–1% of contract per week | Over 2% per week, no justification |
| Cap on total LADs | Capped at 10% of contract value | No cap at all |
| Sectional completions | One LAD rate for whole contract | Separate LAD rate per section |
| Relevant events / EoT | Standard JCT/NEC/AIA list | Restricted or deleted relevant events |
| Notice requirements | Reasonable period (21+ days) | Very short notice periods (7 days) |
| Flow-down from main contract | LADs flow down proportionately | Full main contract LAD rate on sub |