You submitted your interim payment application exactly on time. But two days before you are due to be paid, the main contractor sends a one-line email stating they are withholding £15,000 for “site damages and programme delays”, with no further breakdown. Do you have to accept the hit? Under UK construction law, the answer is an absolute no.
The Legal Mechanism: Section 111 of the Construction Act 1996
Under Section 111 of the Housing Grants, Construction and Regeneration Act 1996, a main contractor cannot withhold money from your notified sum unless they issue a valid Pay Less Notice. To be legally valid, this notice must pass two strict tests:
- The Statutory Timing: The notice must be served no later than the prescribed deadline (under standard JCT, this is 5 clear days before the Final Date for Payment). If it arrives one day late, it is void.
- The Calculation Basis: The notice must state the exact sum the contractor considers to be due and, crucially, the basis on which that sum is calculated. A vague email mentioning “contra-charges” fails this legal test entirely.
The Financial Danger of Accepting Invalid Deductions
Main contractors rely heavily on trade subcontractors not knowing their statutory rights. If you fail to challenge a defective Pay Less Notice, you suffer severe commercial damage:
- Immediate Cash Flow Paralysis: You are left funding materials and labour out of pocket while the main contractor artificially bolsters their own project cash flow.
- Loss of Statutory Leverage: If the notice is legally invalid, the original sum you applied for becomes a statutory debt. You gain the immediate right to suspend works under Section 112 or launch a smash-and-grab adjudication. Accepting the deduction throws away this leverage.
Your Action Plan: Enforce the Notified Sum
If a notice is late or lacks a detailed calculation basis, ignore the deduction. The full amount you applied for is legally due. Do not wait for the final account to argue about it.
I built an automated Pay Less Notice Validity Checker to help you verify these statutory deadlines instantly. Run your dates through my engine, and if the main contractor missed the window, generate a formal Section 111 payment demand to recover your money immediately.