Guide · 8 min read · Updated 2026-07-25
Five Subcontract Clauses That Quietly Eat Your Margin
Nobody loses money on the standard forms. The JCT and NEC families are broadly balanced documents. The money is lost in the schedule of amendments: the twenty or forty pages that arrive with the subcontract order and quietly rewrite who carries which risk.
These are the five amendments that do the most damage to subcontractors, what each one looks like on the page, and what to ask for instead. Read the amendments before you price, because every one of these is cheaper to negotiate at tender than to litigate at final account.
1. Condition precedent notice clauses
The wording to look for: "as a condition precedent to any entitlement", usually attached to variations, loss and expense or extensions of time, with a short notice window. The effect is that a claim notified late is not a weak claim, it is no claim. Courts will generally enforce clear condition precedent wording.
What to ask for: longer windows, notice by any written means rather than a prescribed form, and softening "condition precedent" to an obligation. If it stays, build the discipline to live with it: a same-day notice habit and a weekly check of anything instructed but not yet notified.
2. Pay-when-certified and other payment delays
Pay-when-paid is largely banned by section 113 of the Construction Act, so the same delay now arrives dressed differently: payment periods running from the main contract certificate, long due-date chains, or final payment tied to events entirely outside your control.
What to ask for: payment periods that run from your application, a named final date for payment, and total cycles you can actually fund. Price the cash flow if you cannot change it: sixty days of your turnover has a financing cost, and it belongs in your rate.
3. Liquidated damages passed down without a cap
The amendment passes the main contract LADs down to you in full, sometimes on a package worth a fraction of the damages. A £5,000-a-week exposure on a £60,000 package is not a risk transfer, it is an unpriced insurance policy you are writing.
What to ask for: a cap tied to your subcontract sum or a percentage of it, damages proportionate to your package, and clarity that LADs are the exclusive remedy for delay. If the number stays disproportionate, that is a bid/no-bid signal, not just a pricing item.
4. Retention with a long and conditional tail
Standard retention is painful but predictable. The trap versions release your retention by reference to the main contract: half on a practical completion you do not control, the rest on the making good of defects across the whole project, potentially years after your package finished.
What to ask for: release dates tied to your own works, a retention bond as an alternative, or reduced percentages. At minimum, diarise the release dates and chase them: unclaimed retention across a subcontractor’s ledger is routinely worth more than a bad month.
5. Wide set-off and contra-charge rights
Watch for wording that lets the contractor deduct "any amount due or which may become due" across "this or any other contract". Combined with a weak notice obligation, it turns your payment into a running account the other side can raid, sometimes for disputes on entirely different projects.
What to ask for: set-off limited to this subcontract, only for ascertained sums, and always through a compliant pay-less notice. The Construction Act helps here: deductions taken without the required notice are recoverable in adjudication, and adjudicators see this pattern weekly.
BuildPredict’s contract review reads your subcontract and flags these clause patterns automatically, with the clause reference and a plain-English explanation of what it means for your money.
Frequently asked questions
Can a small subcontractor really negotiate amendments?
More often than you would think, if you ask early and specifically. A tender-stage markup asking for three targeted changes reads as professional, and contractors expect it. What rarely works is signing in silence and arguing later. Even a refused request is useful: it tells you what you are pricing.
Is pay-when-paid ever enforceable in the UK?
Only in the narrow case where the party up the chain is insolvent, which is the exception preserved by section 113 of the Construction Act. Outside that, pay-when-paid wording is ineffective, but watch for certificate-linked payment periods that create similar delay lawfully.
What does condition precedent actually mean?
It means the entitlement only exists if the stated condition is met first. Applied to notices, a valid claim notified one day late can be worth nothing. Clear wording is generally enforced, so treat the notice windows in an amended subcontract as hard commercial deadlines.
Should I get every subcontract legally reviewed?
For high-value or heavily amended orders, a solicitor’s review is cheap insurance. For routine packages, a consistent internal check against a known list of trap clauses catches most of the damage. The worst option is the common one: signing unread because the programme is tight.
This guide is general information for UK construction businesses, not legal advice. Contract terms differ, and for significant disputes or heavily amended contracts you should take professional advice.