Contra charges that survive
Being right about the cost is the easy part. Most contra charges fail not because the money was not spent, but because of how the deduction was made.
QScope Team · 21 March 2026 · 6 min read
A contra charge is a deduction made against a subcontractor for costs incurred as a result of its default: attendance it should have provided, cleaning it did not do, work put right by others, damage caused to another trade.
The costs are usually real. The deductions frequently fail anyway.
The three requirements
1. A contractual right to deduct
The subcontract must give a right of set-off, or the cost must be recoverable under a specific provision. Fairness is not a mechanism. A cost that was plainly caused by the subcontractor, with no contractual route to recover it, is a claim rather than a deduction.
2. Notice, given properly and in time
Where the deduction reduces a sum otherwise payable, the Construction Act notice regime applies. In practice that means a pay less notice, served before its deadline, stating the sum considered due and the basis of calculation.
This is where most contra charges die. The charge is applied inside the valuation, no pay less notice is served, and the subcontractor's application becomes the notified sum in full.
3. Evidence of the cost
Actual cost, evidenced. Invoices, allocation sheets, photographs of the condition being remedied, records of who did the work and how long it took.
Where to put it in the certificate
Not inside the measured work. Not netted against the subcontractor's application. As its own line, below the net valuation, identified as a deduction with its reason stated.
Two reasons. First, it makes the deduction visible to the party being charged, which is both fair and what the notice provisions require in substance. Second, it keeps the valuation clean, so the subcontractor's account and yours agree on the value of the work and differ only on the deduction, which is a much easier conversation.
The categories that cause most trouble
General attendance and cleaning. Often deducted as a round monthly sum with no record of what was actually done. Almost impossible to substantiate.
Damage to other trades. Requires establishing who caused it, which needs a record made at the time, with a photograph and a date.
Delay caused by a subcontractor. The most contentious. Deducting main contract prolongation costs from a subcontract requires establishing causation through the programme, and it is not a matter for a line on a valuation.
Rectification of defective work. The most defensible category, provided the subcontractor was given the opportunity to return and put it right, and declined or failed to. Skipping that step converts a good charge into a weak one.
The sequence that works
- Record the event when it happens, with date, description and photograph
- Notify the subcontractor at the time, giving it the chance to remedy where the contract requires
- Record the actual cost incurred, with supporting documents
- Identify the contractual provision relied on
- Serve the pay less notice before its deadline, stating the sum and the basis
- Show the deduction as its own line on the certificate
Six steps, of which two are about notice and one is about photographs. That distribution reflects where these charges are actually won and lost.
A word on proportionality
Contra charges are also a relationship instrument, and applying small ones aggressively is expensive in ways that do not appear on the job. A subcontractor that expects to be charged for everything prices accordingly next time, or does not price at all.
The charges worth pursuing are the ones large enough to matter and clear enough to substantiate. The rest are usually better dealt with as a conversation, which costs less and works more often.
QScope keeps deductions as their own line on the certificate with a reason attached, so a contra charge is visible to the party being charged instead of buried in a valuation.