Construction Retention: How Contractors Can Stop Losing Money They Have Already Earned

Construction retention is one of the most reliable sources of cash flow pain in the contracting industry. A standard 5-10% withheld from every progress claim adds up quickly - on a £500,000 contract, you could have £25,000 to £50,000 sitting with the client for 12 months or more while you cover payroll, materials, and supplier invoices from your own working capital. The frustration is compounded when that money goes missing not through a formal dispute, but because nobody on your side was tracking when it fell due or had sent the invoice to recover it.

How Retention Accumulates Across a Live Project

Retention is withheld progressively against each interim payment application. On most JCT and NEC contracts, the typical split is 5% held throughout the project, reducing to 2.5% once the contract sum passes 50% practical completion, with the full balance held until practical completion is certified. Some contracts apply a flat rate right through to completion. Either way, by the time you reach practical completion on a mid-sized project, you can have two or three percent of the total contract value still locked with the client - on top of any retention withheld from your sub-contractors, which you are obliged to pass down the supply chain once you receive your own.

For a general contractor running four or five projects simultaneously, outstanding retention across the portfolio can easily reach six figures. The problem is not the mechanism itself - it exists for good reason and most contractors accept it as part of the industry. The problem is what happens to that money over time when it is not tracked systematically.

What Goes Wrong When Retention Is Not Tracked

The failure mode is predictable. Projects complete, snag lists get closed out, and the defect liability period ticks past - but no one sends the invoice to recover the final retention. This happens for two reasons. First, the person managing the job day-to-day moves on to the next project and the administrative tail of the completed job gets deprioritised. Second, there is no system prompting anyone to raise the retention invoice when the DLP expires.

Contractors who rely on memory or generic spreadsheets to track outstanding retention find themselves in a familiar position: a director reviews the accounts, notices the business should have more cash than it does, and then spends a week reconstructing which projects have unclaimed retention and how much. That review often reveals invoices that are 6-12 months overdue - and in some cases, amounts that have fallen outside the contractual notice period required to claim them.

On the sub-contractor side, the problem compounds. You withhold retention from your sub-contractors in parallel with what your client holds from you. If a sub-contractor completes their scope but the overall project runs long, you may be holding their retention for months after their work has been signed off. Failing to release it promptly once it falls due creates friction, damages relationships, and can lead to formal disputes.

The Two Release Points That Require Active Management

Retention releases happen at specific contractual milestones, and each one requires a deliberate action on your part.

Practical completion. When the architect or contract administrator certifies practical completion, this typically triggers release of 50% of held retention. It does not happen automatically - you need to raise a retention invoice promptly. Delays at this stage are common because the project team is focused on the snagging list, not the commercial close-out.

End of defect liability period. The DLP runs for a defined period from practical completion - 12 months is standard, though some contracts specify 6 months or 24 months. When the DLP expires and the client issues a Certificate of Making Good Defects (or equivalent), the remaining retention falls due. This is the release that most often gets missed, because it happens a year after the practical completion energy has dissipated and the job has long been off the radar.

Both milestones need to be in a system, with a task or reminder tied to the contractual date. Without that, you are relying on someone remembering to check a contract document for a job that completed over a year ago.

Building a Basic Retention Tracking Process

You do not need specialist software to start tracking retention properly - the priority is having a reliable record that survives staff changes and project handovers.

For each contract, record the following from the day you win the job: the total contract value, the retention percentage, the expected practical completion date, and the DLP duration. As the project progresses, update the retained amount each time an interim payment is received. When practical completion is certified, log the date and raise the first retention invoice within five working days. Set a calendar reminder for the DLP end date on the day practical completion is achieved - do not wait until you are close to the date.

Businesses that use job management software can tie retention milestones directly to each job record. When the DLP date arrives, the system can trigger a task to raise the retention invoice and mark it against the job. This removes the dependence on individual memory and creates a clear record if there is ever a dispute about whether the payment fell due.

Zigaflow's job tracking and invoicing features allow contractors to attach retention milestones to individual jobs and raise invoices directly against each one, with the full job cost record in the same system. When the invoices sync to Xero or QuickBooks, the outstanding retention appears in your accounts receivable without any manual reconciliation.

What Systematic Retention Tracking Delivers

Contractors who track retention consistently find that the improvement is not just financial - though recovering cash that would otherwise have been written off is significant. The bigger operational gain is predictability. When you know how much retention is outstanding and when it falls due, you can plan working capital with real numbers rather than estimates. Cash flow surprises become less frequent. And the commercial close-out of each project - including the retention conversation with the client - becomes a structured process rather than an afterthought.

Starting with your live projects today, document the DLP end date for each one. If any have passed without a retention invoice being raised, raise them now. That single exercise will often recover more cash than any other administrative change you make this quarter.

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