What Is a Compensation Event Under NEC4? Complete EVM Guide

<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="#the-core-mechanism">The Core Mechanism</a></li><li><a href="#how-ces-adjust-the-evm-baseline">How CEs Adjust the EVM Baseline</a></li><li><a href="#the-19-compensation-events-clause-60-1">The 19 Compensation Events (Clause 60.1)</a></li><li><a href="#why-evm-data-supports-better-ce-quotations">Why EVM Data Supports Better CE Quotations</a></li><li><a href="#worked-example-ce-adjusts-bac-on-a-rail-project">Worked Example: CE Adjusts BAC on a Rail Project</a></li><li><a href="#the-dividing-date-and-ce-assessment">The Dividing Date and CE Assessment</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 compensation event (CE) under NEC4 is any event listed in clause 60.1 that entitles the Contractor to a change in the Prices, the Completion Date, or both. There are 19 categories in the standard form, ranging from the Project Manager giving an instruction that changes the Works Information to physical conditions that differ from what the Site Information described. In <a href="/en/earned-value">earned value management</a> terms, every implemented CE changes your <a href="/en/earned-value/definitions/budget-at-completion">Budget at Completion (BAC)</a> and reshapes your <a href="/en/earned-value/definitions/planned-value">Planned Value</a> baseline. Ignore that link, and your <a href="/en/earned-value/definitions/earned-value-management">EVM</a> data becomes noise.</p><p>This page is part of the <a href="/en/earned-value/definitions">earned value definitions glossary</a>. For a deep dive into the NEC4 CE process itself, see the <a href="/en/nec4/compensation-events">NEC4 compensation events guide</a>.</p><h2 id="the-core-mechanism">The Core Mechanism</h2><p>A compensation event isn't a variation. That distinction matters. Under JCT, you have variations. Under NEC4, you have compensation events. They look similar from a distance, but the mechanism is fundamentally different.</p><p>Under NEC4, the CE process works like this:</p><ol><li>An event occurs (or an instruction is given)</li><li>The Contractor notifies the Project Manager within 8 weeks (clause 61.3)</li><li>The PM decides whether it's a CE</li><li>The Contractor submits a quotation (clause 62)</li><li>The PM accepts, negotiates, or makes their own assessment</li><li>The CE is implemented, Prices and programme adjust</li></ol><p>Miss step 2 and you're time-barred. That's it. No second chances. The <a href="/en/nec4/eight-week-time-bar">eight-week time bar</a> is absolute, and I've watched it kill valid claims worth six figures.</p><h2 id="how-ces-adjust-the-evm-baseline">How CEs Adjust the EVM Baseline</h2><p>Here's where most commercial teams get it wrong. They track CEs in one system and EVM in another. The two never talk to each other.</p><p>When a CE is implemented under clause 65, the Prices change. On an Option C <a href="/en/earned-value/definitions/target-cost">target cost</a> contract, this means the target total of the Prices, your BAC, increases (or occasionally decreases). The <a href="/en/earned-value/definitions/accepted-programme">Accepted Programme</a> should also be updated to reflect any time impact.</p><p>That triggers a cascade through your entire EVM dataset:</p><pre class="ge-ascii-diagram ge-anim"> CE IMPLEMENTED │ ▼ ┌─────────────┐ ┌──────────────────────────┐ │ BAC changes │────▶│ PV baseline must be │ │ (Prices │ │ re-profiled against the │ │ adjusted) │ │ updated programme │ └─────────────┘ └──────────────────────────┘ │ │ ▼ ▼ ┌─────────────┐ ┌──────────────────────────┐ │ EV changes │ │ SPI recalculated against │ │ (new BAC in │ │ new PV baseline │ │ % complete) │ └──────────────────────────┘ └─────────────┘ │ ▼ ┌─────────────┐ ┌──────────────────────────┐ │ CPI changes │────▶│ EAC / ETC forecasts │ │ (EV / AC │ │ update automatically │ │ shifts) │ └──────────────────────────┘ └─────────────┘ </pre><p>If you don't feed implemented CEs into BAC, your <a href="/en/earned-value/definitions/cost-performance-index">CPI</a> looks artificially low. You're measuring actual spend (which includes CE work) against the original budget (which doesn't). The project looks like it's haemorrhaging money when it's actually delivering additional scope that's been properly compensated.</p><h2 id="the-19-compensation-events-clause-60-1">The 19 Compensation Events (Clause 60.1)</h2><p>Not all CEs are created equal. Some happen constantly. Others are rare. Here's how they break down in practice:</p><div class="ge-table-wrap ge-anim"><table class="ge-table"><thead><tr><th>#</th><th>Clause</th><th>Event</th><th>Frequency</th></tr></thead><tbody><tr><td>1</td><td>60.1(1)</td><td>PM gives an instruction changing the Works Information</td><td>Very common</td></tr><tr><td>2</td><td>60.1(2)</td><td>Client doesn't provide something by the date shown</td><td>Common</td></tr><tr><td>3</td><td>60.1(3)</td><td>Client gives an instruction to stop or not to start work</td><td>Occasional</td></tr><tr><td>4</td><td>60.1(4)</td><td>Client doesn't reply to a communication within the period</td><td>Common</td></tr><tr><td>5</td><td>60.1(5)</td><td>Client doesn't allow access by the access date</td><td>Occasional</td></tr><tr><td>6</td><td>60.1(6)</td><td>Client doesn't provide materials, facilities, or samples</td><td>Rare</td></tr><tr><td>7</td><td>60.1(7)</td><td>PM withholds acceptance of a submission for a reason not stated</td><td>Rare</td></tr><tr><td>8</td><td>60.1(8)</td><td>PM changes a decision previously communicated</td><td>Occasional</td></tr><tr><td>9</td><td>60.1(9)</td><td>PM instructs a search that finds nothing wrong</td><td>Common</td></tr><tr><td>10</td><td>60.1(10)</td><td>PM withholds acceptance of programme for a reason not in clause 31.3</td><td>Rare</td></tr><tr><td>11</td><td>60.1(11)</td><td>Supervisor instructs tests or inspections not in the Works Information</td><td>Occasional</td></tr><tr><td>12</td><td>60.1(12)</td><td>Physical conditions which an experienced contractor wouldn't have foreseen</td><td>Common</td></tr><tr><td>13</td><td>60.1(13)</td><td>Weather event that occurs less often than once in 10 years</td><td>Occasional</td></tr><tr><td>14</td><td>60.1(14)</td><td>Event that's an Employer's risk</td><td>Occasional</td></tr><tr><td>15</td><td>60.1(15)</td><td>PM certifies take over of a part before Completion</td><td>Rare</td></tr><tr><td>16</td><td>60.1(16)</td><td>Client doesn't provide correct information in the Site Information</td><td>Common</td></tr><tr><td>17</td><td>60.1(17)</td><td>PM notifies a correction to an assumption about a CE</td><td>Occasional</td></tr><tr><td>18</td><td>60.1(18)</td><td>A breach of contract by the Client that isn't covered above</td><td>Rare</td></tr><tr><td>19</td><td>60.1(19)</td><td>PM instructs a change to a Key Date</td><td>Occasional</td></tr></tbody></table></div><p>On a typical £30M infrastructure project running 24 months, I'd expect to see 30 to 60 CEs notified. Maybe 40% of those come from clause 60.1(1), PM instructions. Another 20% from ground conditions under 60.1(12). The rest scatter across the other 17 categories.</p><h2 id="why-evm-data-supports-better-ce-quotations">Why EVM Data Supports Better CE Quotations</h2><p>This is the bit most people miss. Your EVM data doesn't just get affected by CEs. It actively strengthens your CE quotations.</p><p>When you submit a quotation under clause 62, the PM is assessing whether your costs are reasonable. If you can show that your project-wide <a href="/en/earned-value/definitions/cost-performance-index">CPI</a> is 0.95, that tells them your overall cost efficiency is strong. Any cost increase in the CE quotation is genuinely attributable to the compensable event, not to the Contractor's inefficiency.</p><p>Conversely, if your CPI is 0.78, expect the PM to push back. They'll argue (sometimes rightly) that some of the cost in your quotation reflects your own underperformance rather than the CE impact.</p><p>Strong EVM discipline is commercial ammunition. It separates CE costs from baseline inefficiency. That distinction is worth real money.</p><h2 id="worked-example-ce-adjusts-bac-on-a-rail-project">Worked Example: CE Adjusts BAC on a Rail Project</h2><span class="ge-worked-label">Worked Example</span><div class="ge-callout ge-anim"><p><strong>Scenario:</strong> Costain is delivering a £30M NEC4 Option C rail electrification package for Network Rail. Original BAC (target total of the Prices) = £30,000,000. The Accepted Programme runs from March 2025 to June 2027.</p><p>In August 2025, during foundation works for an overhead line mast at chainage 42+350, the team encounters contaminated ground that wasn't shown in the Site Information. This is a CE under clause 60.1(12).</p><p><strong>Timeline:</strong></p><ul><li><strong>15 August 2025:</strong> Contamination discovered. Site supervisor records details in the site diary.</li><li><strong>18 August 2025:</strong> Contractor notifies the PM under clause 61.3 (3 days after awareness, well within the 8-week time bar).</li><li><strong>25 August 2025:</strong> PM accepts it's a CE and instructs the Contractor to submit a quotation.</li><li><strong>15 September 2025:</strong> Contractor submits quotation: £1,800,000 additional <a href="/en/earned-value/definitions/defined-cost">Defined Cost</a> + 3 weeks' time impact.</li><li><strong>29 September 2025:</strong> PM accepts the quotation. CE is implemented under clause 65.</li></ul><p><strong>EVM Impact:</strong></p><div class="ge-table-wrap ge-anim"><table class="ge-table"><thead><tr><th>Metric</th><th>Before CE</th><th>After CE</th></tr></thead><tbody><tr><td>BAC</td><td>£30,000,000</td><td>£31,800,000</td></tr><tr><td>PV at month 6 (per updated programme)</td><td>£8,400,000</td><td>£8,400,000 (CE work profiled from month 8)</td></tr><tr><td>EV at month 6</td><td>£7,560,000 (25.2% of £30M)</td><td>£7,560,000 (recalculated as 23.8% of £31.8M)</td></tr><tr><td>AC at month 6</td><td>£8,100,000</td><td>£8,100,000</td></tr><tr><td>CPI (old BAC)</td><td>0.933</td><td>–</td></tr><tr><td>CPI (new BAC)</td><td>–</td><td>0.933</td></tr></tbody></table></div><p>Note that at month 6, the CE hasn't yet affected EV or AC because the contamination work is profiled from month 8 onwards. But BAC changes immediately upon implementation. As the CE work progresses through months 8 to 10, the additional £1.8M flows through both EV (as work is completed) and AC (as costs are incurred).</p><p><strong>The commercial value:</strong> Without updating BAC, by month 12 the team would be reporting CPI against £30M while spending against £31.8M of scope. That's a phantom overrun of £1.8M that doesn't exist.</p></div><h2 id="the-dividing-date-and-ce-assessment">The Dividing Date and CE Assessment</h2><p>CEs are assessed prospectively from the <a href="/en/nec4/dividing-date">dividing date</a>, the date the PM decides a CE is one, or should have decided. This matters for EVM because the assessment uses forecast costs from the dividing date forward, not historical actual costs.</p><p>Don't mix these up. The CE quotation is a prospective forecast. Your EVM tracks actual spend. The two converge over time as the CE work completes, but they start from entirely different reference points. I've seen QSs try to back-calculate a CE quotation from EVM actuals. That's wrong, and it'll get rejected.</p><h2 id="common-mistakes">Common Mistakes</h2><p><strong>1. Not updating BAC after CE implementation.</strong> The single most common mistake. Every implemented CE should trigger a BAC update on the same day. No exceptions. Set a process, make someone accountable, and check it monthly.</p><p><strong>2. Tracking CEs in a separate spreadsheet from EVM.</strong> If your CE register and your EVM tracker are different files (or worse, managed by different people), they will diverge. Guaranteed. The CE register should feed directly into BAC.</p><p><strong>3. Confusing CE notification with CE implementation.</strong> A notified CE doesn't change BAC. Only an implemented CE changes the Prices. You might have 15 notified CEs sitting in the pipeline. None of them should be in your BAC until the PM implements them. Track them as potential BAC adjustments in your <a href="/en/earned-value/definitions/estimate-at-completion">EAC</a> forecast, but keep them out of the baseline.</p><p><strong>4. Forgetting the time impact in PV.</strong> A CE might add £500K to BAC and 4 weeks to the programme. If you update BAC but don't re-profile PV against the revised programme, your SPI is wrong. Both changes must flow through together.</p><p><strong>5. Missing the 8-week time bar.</strong> This isn't an EVM mistake. It's a commercial catastrophe. If you don't notify within 8 weeks of becoming aware of the event, you lose the right to claim. That means no BAC adjustment, no time extension, and a genuine cost overrun eating into your margin.</p><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>Does every CE change BAC?</h3><p>Every CE that results in a change to the Prices will change BAC. Some CEs only affect the Completion Date (time but no cost). Others affect only cost. Most affect both. The key is implementation, until the CE is formally implemented under clause 65, BAC doesn't change. Notified CEs in the quotation pipeline are forecast adjustments, not baseline changes.</p><h3>How do CEs affect CPI and SPI?</h3><p>Once implemented, the CE increases BAC, which means your percentage complete (EV / BAC) drops slightly because the denominator has grown. As the CE work progresses and EV accumulates, it normalises. If you don't update BAC, CPI appears artificially low because actual cost includes CE work but the budget doesn't reflect it. SPI is affected through the programme update, the new Accepted Programme re-profiles PV.</p><h3>What's the difference between a CE and a variation?</h3><p>Under NEC4, there are no "variations." The compensation event mechanism replaces the traditional variation process found in JCT and other contract forms. CEs cover a broader range of events than traditional variations, they include not just changes to the works, but also Client failures, weather events, and physical conditions. The quotation process is also different: the Contractor proposes the cost and time impact, whereas under JCT, variations are typically valued using contract rates.</p><h3>Can a CE reduce BAC?</h3><p>Yes, but it's uncommon. A CE that removes scope (for example, the PM instructs deletion of a section of works under clause 60.1(1)) would reduce the Prices and therefore reduce BAC. In practice, most CEs increase BAC. A reduction is technically called a "negative compensation event" and follows the same quotation process.</p></article></div>