Variance Threshold in Earned Value: How to Set Effective Limits

<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="#what-thresholds-actually-do">What Thresholds Actually Do</a></li><li><a href="#the-threshold-matrix">The Threshold Matrix</a></li><li><a href="#setting-the-right-thresholds">Setting the Right Thresholds</a></li><li><a href="#worked-example-thresholds-in-action">Worked Example: Thresholds in Action</a></li><li><a href="#why-thresholds-need-both-and-values">Why Thresholds Need Both % and £ Values</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>A variance threshold is a predefined limit, expressed as a percentage, an absolute £ amount, or both, that triggers a formal management review when a control account's cost or schedule performance crosses it. Without thresholds, <a href="/en/earned-value">earned value management</a> is just a dashboard people glance at. With them, it's an early warning system that forces action before problems become crises.</p><p>This term is part of the <a href="/en/earned-value/definitions">earned value definitions glossary</a>. For how thresholds feed into formal reporting, see the <a href="/en/earned-value/definitions/variance-analysis-report">variance analysis report</a> page.</p><h2 id="what-thresholds-actually-do">What Thresholds Actually Do</h2><p>Thresholds turn EVM data into management decisions. They answer the question: "At what point do we stop monitoring and start intervening?"</p><p>Every <a href="/en/earned-value/definitions/control-account-manager">Control Account Manager</a> has a budget and a schedule. Every month, variances are calculated. Without thresholds, a CAM with a <a href="/en/earned-value/definitions/cost-performance-index">CPI</a> of 0.91 might shrug and say "we'll catch up next month." With a threshold set at CPI < 0.95, that same CAM has to write a <a href="/en/earned-value/definitions/variance-analysis-report">VAR</a>, identify root causes, and commit to corrective actions. The threshold is the mechanism that makes EVM actionable rather than informational.</p><h2 id="the-threshold-matrix">The Threshold Matrix</h2><p>Most UK construction projects running EVM use a three-tier system. I've found this works well because it creates graduated responses rather than a single panic button.</p><pre class="ge-ascii-diagram ge-anim">VARIANCE THRESHOLD MATRIX ================================================ MINOR SIGNIFICANT CRITICAL (Monitor) (VAR Required) (Escalate) +--------------+ +--------------+ +--------------+ CV% | -3% to -5% | | -5% to -10% | | &gt; -10% | +--------------+ +--------------+ +--------------+ CV£ | -£50K to | | -£100K to | | &gt; -£250K | | -£100K | | -£250K | | | +--------------+ +--------------+ +--------------+ SV% | -3% to -5% | | -5% to -10% | | &gt; -10% | +--------------+ +--------------+ +--------------+ CPI | 0.95 to 0.97 | | 0.90 to 0.95 | | &lt; 0.90 | +--------------+ +--------------+ +--------------+ SPI | 0.95 to 0.97 | | 0.90 to 0.95 | | &lt; 0.90 | +--------------+ +--------------+ +--------------+ ACTIONS: MINOR: CAM notes variance, monitors next period SIGNIFICANT: CAM writes VAR within 5 working days CRITICAL: VAR + escalation to Project Director + recovery plan</pre><p>The percentages and £ values aren't universal. They depend on project size, risk appetite, and client requirements. A £5M project might set the significant threshold at -3% and £30K. A £200M programme might tolerate -5% and £500K before triggering a VAR.</p><h2 id="setting-the-right-thresholds">Setting the Right Thresholds</h2><p>This is where most teams get it wrong. Set thresholds too tight and you'll drown in VARs. Set them too loose and problems fester undetected.</p><p><strong>The sizing principle:</strong> thresholds should flag genuine problems while filtering out statistical noise. On a £2M control account, a -3% cost variance is £60K. That could be a rounding issue or a delayed invoice. A -8% variance is £160K. That's real.</p><p>Here's a rough guide based on control account size:</p><div class="ge-table-wrap ge-anim"><table class="ge-table"><thead><tr><th>CA Budget</th><th>Significant CV%</th><th>Significant CV£</th><th>Rationale</th></tr></thead><tbody><tr><td>< £500K</td><td>-5%</td><td>-£25K</td><td>Small CAs swing more on % basis</td></tr><tr><td>£500K to £2M</td><td>-5%</td><td>-£75K</td><td>Standard range for most packages</td></tr><tr><td>£2M to £5M</td><td>-5%</td><td>-£150K</td><td>Larger CAs need larger £ thresholds</td></tr><tr><td>> £5M</td><td>-3%</td><td>-£250K</td><td>Big packages need tighter % control</td></tr></tbody></table></div><p>Notice how the percentage stays fairly constant but the £ amount scales. That's deliberate. A 5% swing on a £300K control account is only £15K. Not worth a formal report. A 5% swing on a £10M package is £500K. Very much worth investigating.</p><h2 id="worked-example-thresholds-in-action">Worked Example: Thresholds in Action</h2><span class="ge-worked-label">Worked Example</span><div class="ge-callout ge-anim"><p><strong>Scenario:</strong> A £25M NEC4 Option C school expansion in Birmingham. The project has 8 control accounts. The project controls team has set these thresholds:</p><ul><li><strong>Significant:</strong> CV > -5% OR CV > -£100K (whichever is breached first)</li><li><strong>Critical:</strong> CV > -10% OR CV > -£250K</li></ul><p><strong>March 2026 reporting period:</strong></p><div class="ge-table-wrap ge-anim"><table class="ge-table"><thead><tr><th>Control Account</th><th><a href="/en/earned-value/definitions/budget-at-completion">BAC</a></th><th><a href="/en/earned-value/definitions/earned-value">EV</a></th><th><a href="/en/earned-value/definitions/actual-cost">AC</a></th><th>CV</th><th>CV%</th><th>Status</th></tr></thead><tbody><tr><td>CA-001 Substructure</td><td>£3,200,000</td><td>£3,100,000</td><td>£3,050,000</td><td>+£50,000</td><td>+1.6%</td><td>OK</td></tr><tr><td>CA-002 Frame</td><td>£4,100,000</td><td>£2,800,000</td><td>£3,080,000</td><td>-£280,000</td><td>-6.8%</td><td><strong>CRITICAL</strong> (> -£250K)</td></tr><tr><td>CA-003 Envelope</td><td>£3,800,000</td><td>£1,900,000</td><td>£1,970,000</td><td>-£70,000</td><td>-1.8%</td><td>OK</td></tr><tr><td>CA-004 M&amp;E</td><td>£5,500,000</td><td>£2,200,000</td><td>£2,340,000</td><td>-£140,000</td><td>-2.5%</td><td><strong>SIGNIFICANT</strong> (> -£100K)</td></tr><tr><td>CA-005 Fit-out</td><td>£3,400,000</td><td>£800,000</td><td>£820,000</td><td>-£20,000</td><td>-0.6%</td><td>OK</td></tr><tr><td>CA-006 External Works</td><td>£2,100,000</td><td>£400,000</td><td>£390,000</td><td>+£10,000</td><td>+0.5%</td><td>OK</td></tr><tr><td>CA-007 Prelims</td><td>£1,900,000</td><td>£1,100,000</td><td>£1,180,000</td><td>-£80,000</td><td>-4.2%</td><td>MINOR</td></tr><tr><td>CA-008 Design</td><td>£1,000,000</td><td>£750,000</td><td>£760,000</td><td>-£10,000</td><td>-1.0%</td><td>OK</td></tr></tbody></table></div><p><strong>Actions required:</strong></p><ul><li>CA-002 (Frame): Critical breach. CAM writes VAR + escalation to project director. The -£280K overrun is driven by steel price inflation and programme acceleration costs. A recovery plan is due within 5 working days.</li><li>CA-004 (M&amp;E): Significant breach. CAM writes <a href="/en/earned-value/definitions/variance-analysis-report">VAR</a> explaining the -£140K overrun. Root cause: additional builders' work for services penetrations not in the original scope.</li><li>CA-007 (Prelims): Minor breach at -4.2%. CAM monitors and reports at next review. If it crosses -5% next month, a VAR will be required.</li></ul></div><h2 id="why-thresholds-need-both-and-values">Why Thresholds Need Both % and £ Values</h2><p>One of the most common mistakes. Teams set thresholds as percentages only. That means a -6% variance on a £100K control account triggers a VAR for a £6K overrun, while a -4% variance on a £10M package doesn't trigger anything despite being a £400K problem.</p><p>Always use both. The "whichever is breached first" rule catches problems at any scale. Small packages are controlled by the % threshold. Large packages are controlled by the £ threshold.</p><h2 id="common-mistakes">Common Mistakes</h2><ol><li><strong>Setting thresholds and never enforcing them.</strong> I've seen project procedures that define beautiful threshold matrices and then nobody writes VARs when they're breached. The thresholds become decorative. If you set them, enforce them. Otherwise you're just generating paperwork.</li><li><strong>Using the same thresholds for every project.</strong> A £5M housing project and a £200M rail programme have completely different risk profiles. Thresholds should be calibrated to project size, complexity, and the client's reporting requirements. Copy-pasting from the last project is lazy and produces either too many or too few triggers.</li><li><strong>Only applying thresholds to cumulative data.</strong> Cumulative CPI smooths out volatility, which is usually good. But it also hides recent deterioration. Consider applying thresholds to both cumulative and current-period metrics. A current-period CPI of 0.75 should trigger concern even if the cumulative CPI is still 0.94.</li><li><strong>Not reviewing thresholds when scope changes.</strong> After major compensation events, control account budgets shift. A £100K threshold that was appropriate for a £2M CA might be too loose after the CA grows to £3.5M through CEs. Review thresholds quarterly.</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>Who sets the variance thresholds?</h3><p>Typically the project controls lead, in consultation with the commercial manager and project director. On client-mandated EVM (common in defence and rail), the client may prescribe thresholds in the contract or works information. Under <a href="/en/earned-value/definitions/eia-748-standard">EIA-748</a>, the contractor's EVMS must define thresholds as part of its analysis and management reporting criteria.</p><h3>Can variance thresholds be different for cost and schedule?</h3><p>Yes, and they often should be. Schedule delays on critical path activities have different commercial consequences than schedule delays on float-heavy activities. Some projects use tighter SV thresholds for activities flagged as critical path and relaxed thresholds for non-critical work. The principle is the same: the threshold should reflect the level of risk.</p><h3>What happens when a control account keeps breaching the threshold?</h3><p>It stays in VAR status. The CAM updates the VAR monthly with progress on corrective actions, revised forecasts, and any new root causes. If corrective actions aren't working after 2-3 months, the VAR should escalate to a recovery plan with options for re-baselining, scope reduction, or additional resources. Persistent breach without effective action is a governance failure.</p></article></div>