What Is Retention in Construction? Cash Flow & EVM Impact

<div class="ge-article-wrapper"><nav class="ge-toc" aria-label="Table of contents"><p class="ge-toc-label">In this article</p><ul class="ge-toc-list"><li><a href="#how-retention-works-the-payment-timeline">How Retention Works: The Payment Timeline</a></li><li><a href="#worked-example-retention-cash-flow-on-a-20m-project">Worked Example: Retention Cash Flow on a £20M Project</a></li><li><a href="#retention-and-earned-value-why-it-matters-for-forecasting">Retention and Earned Value: Why It Matters for Forecasting</a></li><li><a href="#retention-under-different-contract-forms">Retention Under Different Contract Forms</a></li><li><a href="#the-case-for-retention-reform">The Case for Retention Reform</a></li><li><a href="#common-mistakes">Common Mistakes</a></li><li><a href="#frequently-asked-questions">Frequently Asked Questions</a></li></ul></nav><article class="ge-article-body"><p>Retention is a percentage of each interim payment withheld by the client until the contractor achieves practical completion and, separately, corrects any defects during the defects liability period. It's insurance. The client holds back cash to make sure the contractor finishes the job and comes back to fix anything that's wrong. On most UK construction contracts, retention is 5% of the gross valuation, reducing to 2.5% (half retention) at practical completion. The remaining 2.5% is released at the end of the <a href="/en/earned-value/definitions/defects-liability-period">defects liability period</a>. </p><p>Simple mechanism. Enormous cash flow impact. </p><p>On a £20M project, 5% retention means up to £1,000,000 sitting in the client's bank account earning the client interest while the contractor funds the shortfall from their own working capital. For a Tier 1 contractor running 15 projects simultaneously, that's potentially £10M to £15M tied up in retention at any given time. It's one of the biggest cash flow drains in construction, and it's the reason the UK government has been talking about reforming retention for over a decade. </p><p>This term is part of the <a href="/en/earned-value/definitions">earned value definitions glossary</a>. For how retention affects payment forecasting, see the <a href="/en/earned-value/definitions/cash-flow-forecast">cash flow forecast page</a>. </p><h2 id="how-retention-works-the-payment-timeline">How Retention Works: The Payment Timeline</h2><pre class="ge-ascii-diagram ge-anim"> RETENTION DEDUCTION AND RELEASE – £20M PROJECT, 5% RETENTION Payment Gross Retention Net Month Value Deducted Payment ───── ───── ───────── ─────── Month 1 £400K £20K (5%) £380K Month 2 £600K £30K (5%) £570K Month 3 £800K £40K (5%) £760K Month 4 £1,100K £55K (5%) £1,045K ... Month 12 £1,400K £70K (5%) £1,330K ... Month 18 £1,200K £60K (5%) £1,140K ──── PRACTICAL COMPLETION (Month 18) ──────────────────── Retention held at PC: £1,000,000 (5% of £20M) Half retention released: £500,000 returned to contractor Retention still held: £500,000 (2.5%) ──── END OF DEFECTS LIABILITY PERIOD (Month 30) ──────── Remaining retention released: £500,000 (less any deductions for unresolved defects) TIMELINE: ───────────────────────────────────────────────────────── Month: 1 6 12 18 24 30 │ │ │ │ │ │ ▼ ▼ ▼ ▼ ▼ ▼ ──────┼────┼─────┼─────┼══════════┼══════════┼────── │ │ │ │ │ │ Construction │ Practical Defects Final Period │ Completion Liability Retention │ ▲ Period Release │ │ ▲ Retention Half │ accrues retention Full at 5% released release (£500K) (£500K) Cash tied up in retention: Month 1: £20K Month 6: £200K Month 12: £600K Month 18: £1,000K ← PEAK Month 19: £500K (after half release) Month 30: £0K (after final release) </pre><h2 id="worked-example-retention-cash-flow-on-a-20m-project">Worked Example: Retention Cash Flow on a £20M Project</h2><span class="ge-worked-label">Worked Example</span><div class="ge-callout ge-anim"><p><strong>Scenario:</strong> £20M office refurbishment, JCT Design and Build 2024. 18-month programme. Retention at 5%, reducing to 2.5% at practical completion. 12-month defects liability period. Monthly valuations.</p><br><p><strong>The cash flow reality:</strong></p><br><div class="ge-table-wrap ge-anim"><table class="ge-table"><thead><tr><th>Period</th><th>Cumulative Gross Valuation</th><th>Retention Held (5%)</th><th>Net Cash Received</th></tr></thead><tbody><tr><td>Month 3</td><td>£2,400,000</td><td>£120,000</td><td>£2,280,000</td></tr><tr><td>Month 6</td><td>£5,800,000</td><td>£290,000</td><td>£5,510,000</td></tr><tr><td>Month 9</td><td>£10,200,000</td><td>£510,000</td><td>£9,690,000</td></tr><tr><td>Month 12</td><td>£14,600,000</td><td>£730,000</td><td>£13,870,000</td></tr><tr><td>Month 15</td><td>£18,000,000</td><td>£900,000</td><td>£17,100,000</td></tr><tr><td>Month 18 (PC)</td><td>£20,000,000</td><td>£1,000,000</td><td>£19,000,000</td></tr><tr><td>Month 19 (half release)</td><td>£20,000,000</td><td>£500,000</td><td>£19,500,000</td></tr><tr><td>Month 30 (final release)</td><td>£20,000,000</td><td>£0</td><td>£20,000,000</td></tr></tbody></table></div><br><p><strong>The cost of retention to the contractor:</strong></p><br><p>If the contractor's cost of capital is 6% per annum, the financing cost of retention is approximately:</p><p>- Average retention held over 18 months: ~£500,000</p><p>- Cost at 6%: £500,000 x 6% x 1.5 years = <strong>£45,000</strong></p><p>- Plus the half retention held for 12 months after PC: £500,000 x 6% x 1 year = <strong>£30,000</strong></p><p>- <strong>Total financing cost: approximately £75,000</strong></p><br><p>That £75,000 comes straight off the contractor's margin. On a project with a 3% net profit margin (£600,000), retention financing costs represent 12.5% of the profit. That's before we even talk about the risk of the client going insolvent and the retention disappearing entirely.</p><br><p>I've seen it happen. A fit-out contractor on a £8M retail project lost £400,000 in retention when the client company entered administration 6 months after practical completion. Half retention hadn't been released. The money was gone. No retention bond, no trust fund, no protection. Just an unsecured creditor in a long queue.</p></div><h2 id="retention-and-earned-value-why-it-matters-for-forecasting">Retention and Earned Value: Why It Matters for Forecasting</h2><p>Retention doesn't appear directly in standard EVM metrics. <a href="/en/earned-value/definitions/actual-cost">Actual Cost</a> in EVM is the cost incurred by the contractor, not the cash received. But retention matters enormously for cash flow forecasting alongside your EVM reports. </p><p>A project can show CPI of 1.02 and SPI of 0.98, perfectly healthy EVM performance, while the contractor's bank account is screaming because £800K of earned revenue is locked up in retention and won't be released for another 12 months. </p><p>Your <a href="/en/earned-value/definitions/estimate-at-completion">EAC</a> tells you the projected final cost. Your cash flow forecast needs to overlay retention deductions and releases onto that projection. Without it, you know the project will make money but can't tell if it'll run out of cash first. </p><h2 id="retention-under-different-contract-forms">Retention Under Different Contract Forms</h2><div class="ge-table-wrap ge-anim"><table class="ge-table"><thead><tr><th>Contract</th><th>Standard Retention</th><th>Half Release</th><th>Final Release</th></tr></thead><tbody><tr><td>JCT DB 2024</td><td>5% (or as stated)</td><td>At practical completion</td><td>End of rectification period</td></tr><tr><td>NEC4</td><td>Not standard, specified in Contract Data</td><td>At Completion</td><td>End of defects date</td></tr><tr><td>FIDIC Red Book</td><td>5% (or as stated)</td><td>At taking-over certificate</td><td>After defects notification period</td></tr><tr><td>No retention</td><td>Some contracts use retention bonds instead</td><td>Bond released at completion</td><td>Bond expires at defects end</td></tr></tbody></table></div><p>Under NEC4, retention isn't a default mechanism. It has to be included in the Contract Data via Option X16 (Retention). If X16 isn't included, there's no retention. This catches some people out. I've seen commercial teams assume retention applies on NEC4 contracts when it hasn't been specified. Check the Contract Data. Every time. </p><h2 id="the-case-for-retention-reform">The Case for Retention Reform</h2><p>The UK construction industry has been debating retention reform for years. The arguments are familiar. </p><p><strong>Against retention (contractor's view):</strong> It's an interest-free loan from the supply chain to the client. It disproportionately hurts SMEs and subcontractors. It's often released late or disputed. When clients go insolvent, the money vanishes. The government's 2017 consultation on retention in the construction industry received overwhelming support for reform, but legislation hasn't followed. </p><p><strong>For retention (client's view):</strong> Without retention, what incentive does the contractor have to return and fix defects? A retention bond costs the contractor money too. And frankly, some contractors don't come back to fix defects even with retention in place. </p><p>My view? Retention as a mechanism is outdated, but the underlying problem it solves, incentivising defect correction, is real. Retention bonds or project bank accounts are better solutions, but they require the industry to change habits that are decades old. </p><h2 id="common-mistakes">Common Mistakes</h2><ol><li><strong>Not tracking retention as a separate line in cash flow forecasts</strong>: Retention deductions reduce cash receipts. If your cash flow model doesn't account for the 5% withholding, you'll overestimate available cash by up to £1M on a £20M project. Model it. Every month.</li><li><strong>Missing the retention release claim</strong>: Retention doesn't release automatically. The contractor must apply for it. I've seen half retention sit unreleased for 6 months after practical completion simply because nobody submitted the application. That's 6 months of unnecessary financing cost.</li><li><strong>Not protecting retention through the supply chain</strong>: Main contractors deduct retention from subcontractors but may not ring-fence it. If the main contractor goes insolvent, the subcontractor's retention disappears. Project bank accounts (mandated on some public sector contracts) solve this, but they're not universal.</li><li><strong>Ignoring retention in the EAC calculation</strong>: While retention doesn't affect EVM cost metrics directly (AC is cost incurred, not cash received), the <a href="/en/earned-value/definitions/estimate-at-completion">EAC</a> should inform a cash flow forecast that includes retention timing. A project that's profitable on paper but cash-negative for 30 months is a problem.</li><li><strong>Not negotiating retention terms at tender</strong>: Retention percentage, release triggers, and the mechanism for release are all negotiable. Some contractors successfully negotiate 3% instead of 5%, or earlier half-release triggers. Others negotiate retention bonds in lieu of cash retention. If you don't ask, you don't get.</li></ol><div class="ge-product-note ge-anim"><p><strong>How Gather helps.</strong> Gather's AI reads your site diaries daily and maps progress against your cost-loaded programme, giving you accurate earned value data without manual spreadsheet updates. <a href="https://gatherinsights.com/contact">Book a demo</a> to see it working on a live NEC4 project.</p></div><h2 id="frequently-asked-questions">Frequently Asked Questions</h2><h3>Can a client deduct more than 5% retention?</h3><p>The percentage is whatever the contract states. Five percent is the UK industry standard, but contracts can specify more or less. Some infrastructure contracts use 3%. Some bespoke contracts go to 10% (rare and aggressively disadvantageous to the contractor). Under the Housing Grants, Construction and Regeneration Act 1996 (as amended), there's no statutory cap on retention, but an unreasonably high percentage could be challenged as an unfair contract term. </p><h3>What happens to retention if the contractor goes bust?</h3><p>If the contractor becomes insolvent before practical completion, the client typically retains the money and applies it towards the cost of completing the works with another contractor. The client may also have a right to call on any performance bond. The retention effectively becomes part of the client's recovery pot. If there's money left after completion costs, it may be returned to the insolvency practitioner, but in practice there rarely is. </p><h3>Is retention tax-deductible?</h3><p>Retention is deferred revenue, not a tax deduction. The contractor recognises the full gross value of each <a href="/en/earned-value/definitions/interim-valuation">interim valuation</a> as turnover for tax purposes, including the retention element, even though the cash hasn't been received. This means the contractor pays tax on money they haven't actually been paid. Another reason retention is unpopular in the supply chain. </p><h3>How does retention work with NEC4 Option C?</h3><p>Under NEC4 Option C (target cost), if Option X16 is included, retention is deducted from each payment. The mechanism is the same as any other contract form. However, the pain/gain share calculation at final account uses the total <a href="/en/earned-value/definitions/price-for-work-done-to-date">Price for Work Done to Date</a>, which is based on Defined Cost plus Fee. Not on amounts actually paid after retention deduction. So retention doesn't distort the <a href="/en/earned-value/definitions/pain-gain-share">pain/gain share</a> calculation, but it absolutely affects the Contractor's cash position during the works. </p></article></div>