The Five Per Cent Held Back: A Retention Ledger for UK Subcontractors

Retention is one of the few payment mechanisms in UK construction that can hold back a supplier’s own money without any suggestion of dispute. A main contractor withholds a percentage of each valuation, often five per cent, and the subcontractor carries that deduction in the hope that it will be released at practical completion or after the defects period. The arrangement is familiar, contractual and entirely lawful. It is also a persistent source of cash-flow distortion, because the money is rarely tracked with the same discipline as an ordinary invoice.

The difficulty is not that retention exists. It is that retention release depends on events, certificates and notices that sit outside the supplier’s usual sales ledger. A finance team can invoice a valuation on a Friday and recognise the gross amount in its forecast, while the retained portion has no obvious due date and no routine chase. Over several projects, those withheld amounts become a pool of deferred income that is difficult to reconcile and easy to forget. For a subcontractor operating on thin margins, that pool can be the difference between a comfortable quarter and a short-term funding requirement.

Why retention disappears from the forecast

Most cash-flow forecasts are built around invoice dates and agreed payment terms. Retention does not fit neatly into either. It is created by a deduction on a payment application, but it is not usually due on the same terms as the underlying works. It may be released in two stages, with one portion linked to practical completion and the remainder linked to the end of a defects period. Those stages can be months apart, and the contractual wording may require a certificate, a notice or a final account agreement before payment becomes due.

A supplier that records only the net payment received is recording the symptom rather than the cause. The retained balance then appears as a reduction in turnover rather than as an asset awaiting release. That is a planning error with practical consequences. It understates the value of work already performed, overstates the permanent cash cost of the project and makes it harder to demonstrate the true ageing of receivables when credit is reviewed.

Retention should be treated as a separate class of receivable. It has its own due date, its own evidence requirements and its own risk of delay. Once that distinction is made, the question changes from why the payment was lower than expected to when the withheld amount becomes payable and what must happen first.

The trigger is not the calendar

A common mistake is to assume that retention becomes due automatically after a fixed period. In practice, release is usually triggered by a contractual milestone, and the milestone must be evidenced. Practical completion may be certified by the employer, the contract administrator or another named party. The defects period may begin on a date that is not the same as the date on which the subcontractor finished its own works. A final account may need to be agreed before the remaining balance is released.

The supplier therefore needs to read the retention clause as an operational checklist rather than a general statement. Which event starts the clock? Who must certify it? Is a notice required from the subcontractor? Does the main contractor have a period in which to issue a payless notice or a statement of account? Are there separate release dates for different sections or phases of the works?

These questions matter because a supplier cannot chase a debt that has not yet fallen due, but it can prepare the evidence in advance. Waiting until the defects period has ended before checking the contractual machinery is how retention becomes permanent free credit. The main contractor is not obliged to release money earlier than the contract allows, but the supplier is entitled to know when the release date has passed and to act promptly when it has.

Four columns of a retention ledger

A workable retention ledger does not need complex software. It needs consistency. At minimum, each project should record four things: the retention percentage and any cap, the amount withheld to date, the release trigger and release date, and the evidence required to support release.

The first column should reflect the contract itself. Some contracts cap retention at a stated sum. Others apply different percentages to different elements. A ledger that applies a single percentage to every valuation will misstate the balance. The second column should reconcile the cumulative retention withheld against the payment applications and the main contractor’s payment notices. Discrepancies should be queried while the project is live, not after the final account has been presented.

The third column is the release date, but it should be recorded as a trigger date rather than a guess. If practical completion is certified on a particular date, the ledger should show that date and the contractual period that follows. If the defects period ends on a later date, that should be a separate line. The fourth column is the evidence file: the certificate, the notice, the correspondence confirming completion of remedial works and any final account statement. Without that file, a supplier may know that money is due but be unable to prove it quickly.

From ledger to recovery

A retention ledger is only useful if it produces action. The simplest discipline is to review it monthly alongside the sales ledger. Any release date falling within the next sixty days should be flagged, and the evidence pack should be checked before the date arrives. If the contract requires the supplier to issue a notice or application for release, that step should be diarised rather than left to memory.

When the release date passes, the supplier should invoice or apply for the retained amount in the manner required by the contract. The request should refer to the relevant clause, the trigger event and the evidence already provided. If payment does not follow, the ordinary late-payment disciplines apply: a dated reminder, a statement of the amount due and, where appropriate, reference to statutory interest and compensation under the late-payment framework. The point is not to escalate unnecessarily, but to ensure that a retention balance does not sit in a separate, unchallenged category simply because it was withheld at source.

When release is overdue

Overdue retention is still overdue debt. It should be aged, reconciled and pursued with the same evidence standards as an unpaid invoice. A supplier should be alert to the difference between a legitimate query about defects and a general refusal to release. If remedial work is outstanding, the contractual position may allow the main contractor to withhold the balance; if the works are complete and the period has expired, the absence of a certificate may be an administrative delay rather than a defence.

Retention will remain a feature of UK construction procurement. The supplier’s protection lies in treating it as a receivable from the outset, not as an afterthought once the project team has moved on. A retention ledger that records triggers, evidence and release dates turns a silent deduction into a managed cash-flow item. That is the practical difference between money left on site and money brought back to the business.