What Is Final Account in Construction? EVM Forecasting

<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-definition">The Definition</a></li><li><a href="#how-final-account-builds-up">How Final Account Builds Up</a></li><li><a href="#evm-forecasting-vs-traditional-final-account">EVM Forecasting vs Traditional Final Account</a></li><li><a href="#worked-example-eac-predicting-final-account">Worked Example: EAC Predicting Final Account</a></li><li><a href="#on-nec4-final-assessment-not-final-account">On NEC4: Final Assessment, Not Final Account</a></li><li><a href="#variance-at-completion-the-evm-metric-for-final-account-risk">Variance at Completion: The EVM Metric for Final Account Risk</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 final account is the agreed total cost of a construction project after every variation, claim, compensation event, and adjustment has been settled. It's the number that goes on the balance sheet. The number that determines whether you made money or lost it. And yet, on most projects, nobody has a reliable forecast of what the final account will be until they're six months into arguing about it.</p><p>That's where <a href="/en/earned-value">earned value management</a> changes the game. EVM's <a href="/en/earned-value/definitions/estimate-at-completion">Estimate at Completion</a> (EAC) gives you a data-driven forecast of final outturn months before the traditional final account negotiation even starts.</p><p>Final account is part of the <a href="/en/earned-value/definitions">earned value definitions glossary</a>. For the forecasting formulas that predict final account, see the <a href="/en/earned-value/eac-etc-tcpi">EAC, ETC and TCPI page</a>.</p><h2 id="the-definition">The Definition</h2><div class="ge-formula-box ge-anim"><span class="ge-formula-label">Formula</span><code>Final account = original contract sum + approved variations + settled claims + adjustments - deductions</code></div><p>It sounds straightforward. It never is. On a £22M contract, the final account might end up at £25M after 47 variations, a prolongation claim, and 14 months of negotiation. The problem isn't the arithmetic. The problem is that nobody agrees on the inputs until the very end.</p><p>Traditional final account preparation is retrospective. You finish the work, compile the records, negotiate for months (sometimes years), and arrive at a figure. EVM's <a href="/en/earned-value/definitions/estimate-at-completion">EAC</a> does the opposite. It forecasts the final figure in real time, every month, based on actual performance data.</p><h2 id="how-final-account-builds-up">How Final Account Builds Up</h2><pre class="ge-ascii-diagram ge-anim"> FINAL ACCOUNT BUILD-UP ═══════════════════════ Original Contract Sum £22,000,000 ────────────────────────────────────────────────── + Variation 1 (client design change) +£380,000 + Variation 2 (ground conditions) +£720,000 + Variation 3 (additional M&amp;E scope) +£440,000 + 44 minor variations +£860,000 ────────────────────────────────────────────────── Subtotal: Adjusted Contract Sum £24,400,000 ────────────────────────────────────────────────── + Prolongation claim (12 weeks) +£580,000 + Disruption claim +£190,000 - Contra charges (defects) -£65,000 - Deduction (incomplete landscaping) -£110,000 - Liquidated damages (0 weeks applied) £0 ────────────────────────────────────────────────── FINAL ACCOUNT £24,995,000 ══════════════════════════════════════════════════ EAC PREDICTION (at month 15): £24,500,000 ───────────────────────────────────────────────── Variance (EAC vs Final Account): -£495,000 Accuracy: 98.0% </pre><p>That 98% accuracy at month 15 of a 24-month project isn't unusual when EVM is implemented properly. I've seen it consistently on projects where <a href="/en/earned-value/definitions/cost-performance-index">CPI</a> has stabilised by month 4 or 5. Traditional forecasting at the same stage? Commercial managers guessing within 5-10%, which on a £25M project is a £1.25M to £2.5M margin of error.</p><h2 id="evm-forecasting-vs-traditional-final-account">EVM Forecasting vs Traditional Final Account</h2><p>This is the comparison that matters. Not which method is "better" in theory, but which one gives you actionable information sooner.</p><div class="ge-table-wrap ge-anim"><table class="ge-table"><thead><tr><th>Aspect</th><th>Traditional Final Account</th><th>EVM Forecasting (<a href="/en/earned-value/definitions/estimate-at-completion">EAC</a>)</th></tr></thead><tbody><tr><td><strong>When you get a forecast</strong></td><td>After completion, during negotiation</td><td>Every month from month 3 onwards</td></tr><tr><td><strong>Data source</strong></td><td>Measured quantities, negotiated rates, claims</td><td><a href="/en/earned-value/definitions/earned-value">EV</a>, <a href="/en/earned-value/definitions/actual-cost">AC</a>, <a href="/en/earned-value/definitions/cost-performance-index">CPI</a>, <a href="/en/earned-value/definitions/schedule-performance-index">SPI</a></td></tr><tr><td><strong>Objectivity</strong></td><td>Heavily negotiated, depends on use</td><td>Arithmetic, CPI doesn't negotiate</td></tr><tr><td><strong>Accuracy at 50% complete</strong></td><td>+/- 10-15% (industry research)</td><td>+/- 5-8% (EAC = BAC/CPI, stable CPI)</td></tr><tr><td><strong>Accuracy at 80% complete</strong></td><td>+/- 3-5%</td><td>+/- 1-3%</td></tr><tr><td><strong>Time to settle</strong></td><td>6-18 months after completion (typical)</td><td>Known in real time, verified at completion</td></tr></tbody></table></div><p>The numbers speak for themselves. But here's the thing most people miss: EVM doesn't replace the final account. You still need to go through the formal process of agreeing measured quantities, rates, and claims. What EVM does is tell you where you'll land, so you can negotiate from a position of knowledge instead of hope.</p><h2 id="worked-example-eac-predicting-final-account">Worked Example: EAC Predicting Final Account</h2><span class="ge-worked-label">Worked Example</span><div class="ge-callout ge-anim"><p><strong>Scenario:</strong> A £22M JCT Design and Build contract for a secondary school in Birmingham. The programme is 20 months. At month 15, the QS runs the EVM numbers.</p><p><strong>At month 15 (75% through programme):</strong></p><ul><li><a href="/en/earned-value/definitions/budget-at-completion">BAC</a> = £23.4M (original £22M + £1.4M of agreed variations)</li><li><a href="/en/earned-value/definitions/earned-value">EV</a> = £16,380,000 (70% complete)</li><li><a href="/en/earned-value/definitions/actual-cost">AC</a> = £17,100,000</li><li>CPI = £16,380,000 / £17,100,000 = <strong>0.958</strong></li><li>SPI = 0.93 (slightly behind programme)</li></ul><p><strong>EAC (BAC/CPI):</strong> £23,400,000 / 0.958 = <strong>£24,425,000</strong></p><p>The QS forecasts a final account of approximately £24.4M, a £2.4M increase on the original contract sum, or about £1M over the variation-adjusted figure.</p><p><strong>14 months later (month 29, during final account negotiation):</strong></p><ul><li>Final account agreed at <strong>£24,820,000</strong></li><li>EAC variance: £24,820,000 - £24,425,000 = £395,000</li><li>Forecast accuracy: <strong>98.4%</strong></li></ul><p>The £395,000 difference came from a late defects claim and a disputed daywork account that wasn't in the month-15 data. Had the QS used the CPI x SPI formula, the EAC would have been £24,850,000, almost exactly right.</p></div><h2 id="on-nec4-final-assessment-not-final-account">On NEC4: Final Assessment, Not Final Account</h2><p>Worth clarifying terminology. NEC4 doesn't use the term "final account." It has a formal mechanism called the final assessment under clause 53. The concept is similar, it's the last payment calculation, but the process is different.</p><p>Under NEC4 clause 53, the Project Manager issues the final assessment within 4 weeks of the Defects Certificate. On Option C, this triggers the final pain/gain share calculation. The total of the Prices minus the Price for Work Done to Date determines whether the contractor gets a gain share payment or owes the client a pain share deduction.</p><p>For the full breakdown of the NEC4 final assessment mechanism, see the <a href="/en/earned-value/definitions/final-assessment">final assessment definition page</a>.</p><h2 id="variance-at-completion-the-evm-metric-for-final-account-risk">Variance at Completion: The EVM Metric for Final Account Risk</h2><p>VAC (Variance at Completion) tells you the gap between budget and forecast:</p><p><strong>VAC = BAC - EAC</strong></p><p>Negative VAC means the forecast exceeds the budget. On the school example: VAC = £23,400,000 - £24,425,000 = -£1,025,000. A million-pound problem, spotted 5 months before completion. That's 5 months to do something about it, renegotiate subcontract packages, tighten prelims, challenge disputed variations.</p><p>Without EVM, you discover that million-pound gap during final account negotiation, when it's too late to influence the outcome.</p><h2 id="common-mistakes">Common Mistakes</h2><ol><li><strong>Treating final account as a formality.</strong> It isn't. I've seen final account negotiations that recovered £800,000 of margin on a £15M contract. And I've seen teams lose £600,000 by failing to substantiate legitimate variations. The final account is the last commercial lever you have. Take it seriously.</li></ol><ol><li><strong>Not starting final account preparation during the works.</strong> If you wait until completion to compile your records, you've already lost. Records go missing. People leave the project. Memories fade. Start building the final account file from month 1.</li></ol><ol><li><strong>Ignoring EAC forecasts.</strong> If your EAC says the project will cost £24.5M and you're telling the board it'll be £23M because "we'll recover it in the final account," you're gambling. EAC is telling you what the data says. Listen to it.</li></ol><ol><li><strong>Confusing interim valuations with final account figures.</strong> Interim applications are estimates for payment purposes. The final account is the definitive calculation. They often differ significantly, especially on re-measurable contracts where provisional quantities get finalised.</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>How long does final account settlement typically take?</h3><p>On average, 6 to 18 months after practical completion. Some drag on for years, especially where claims are disputed. Under NEC4, the final assessment mechanism imposes stricter timelines, 4 weeks from the Defects Certificate. But in practice, even NEC4 final assessments can take months if compensation events are still being resolved.</p><h3>Can EAC replace the final account process?</h3><p>No. EAC is a forecast. The final account is a legal settlement. You still need to agree measured quantities, finalise rates, settle claims, and reach a formal figure both parties sign off on. EAC tells you where you're heading. The final account tells you where you arrived.</p><h3>What's the difference between final account and final certificate?</h3><p>The final account is the agreed financial position. The final certificate (JCT terminology) or Defects Certificate (NEC4) is the formal document issued after the defects liability period expires, confirming all defects have been made good. The certificate often triggers the final account process.</p><h3>How accurate is EAC compared to traditional forecasting?</h3><p>Research consistently shows that EAC (using BAC/CPI) produces forecasts within 5-10% of the final outturn once <a href="/en/earned-value/definitions/cost-performance-index">CPI</a> stabilises (typically by month 3-4). Traditional commercial forecasting relies on the QS's judgement and is typically accurate to 10-15% at the same stage. The gap narrows as the project approaches completion, but EVM gives you earlier, more reliable signals.</p></article></div>