What Is Undistributed Budget (UB) in EVM?

<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-ub-fits-into-the-budget-structure">How UB Fits Into the Budget Structure</a></li><li><a href="#why-ub-exists">Why UB Exists</a></li><li><a href="#worked-example-ce-creates-ub-on-a-rail-package">Worked Example: CE Creates UB on a Rail Package</a></li><li><a href="#why-ub-matters">Why UB Matters</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>Undistributed Budget (UB) is the portion of your Performance Measurement Baseline (PMB) that's been authorised but hasn't yet been allocated to specific control accounts or work packages. Think of it as budget in limbo. It exists. It's real money. But nobody owns it yet because the scope it covers hasn't been broken down into measurable work. On a £40M highways scheme running NEC4 Option C, I've seen UB sit at over £800K for months after a batch of compensation events were implemented but the commercial team hadn't decomposed them into work packages.</p><p>UB is part of the <a href="/en/earned-value/definitions">earned value definitions glossary</a>. For the full picture of how budgets flow through an EVM system, see the <a href="/en/earned-value">earned value management guide</a>.</p><h2 id="the-definition">The Definition</h2><div class="ge-formula-box ge-anim"><span class="ge-formula-label">Formula</span><code>Undistributed Budget (UB) = authorised budget not yet assigned to control accounts or work packages</code></div><p>UB sits inside the PMB. It's approved scope with approved budget, but it hasn't been planned in detail yet. The moment you decompose that scope into work packages and assign it to a <a href="/en/earned-value/definitions/control-account-manager">Control Account Manager</a>, UB drops and the control account <a href="/en/earned-value/definitions/budget-at-completion">BAC</a> increases by the same amount.</p><p>Here's the critical distinction: UB is not Management Reserve (MR). MR sits outside the PMB and covers unknown unknowns. UB sits inside the PMB and covers known scope that simply hasn't been planned yet.</p><h2 id="how-ub-fits-into-the-budget-structure">How UB Fits Into the Budget Structure</h2><pre class="ge-ascii-diagram ge-anim">CONTRACT BUDGET BASE (CBB) ============================================= | | | PERFORMANCE MEASUREMENT BASELINE (PMB) | | +-------------------------------------+ | | | | | | | Control Account Budgets | | | | (distributed to CAMs) | | | | | | | | CA-001: £2,400,000 | | | | CA-002: £3,100,000 | | | | CA-003: £1,850,000 | | | | CA-004: £4,200,000 | | | | . | | | | Total Distributed: £18,550,000 | | | | | | | +-------------------------------------+ | | | | | | | UNDISTRIBUTED BUDGET (UB) | | | | CE-015: £320,000 (awaiting WP) | | | | CE-018: £130,000 (awaiting WP) | | | | Total UB: £450,000 | | | | | | | +-------------------------------------+ | | | | PMB Total = £19,000,000 | | | +-------------------------------------------+ | | | MANAGEMENT RESERVE (MR) | | £1,000,000 | | | +-------------------------------------------+ CBB = PMB + MR = £20,000,000 PMB = Distributed Budgets + UB = £19,000,000</pre><p>The key equation:</p><p><strong>PMB = Sum of all Control Account Budgets + UB</strong></p><p>And:</p><p><strong>CBB = PMB + Management Reserve</strong></p><h2 id="why-ub-exists">Why UB Exists</h2><p>UB doesn't exist because someone's being lazy. It exists because real construction projects don't work in neat sequential steps. Three common scenarios create UB:</p><p><strong>1. Compensation events approved but not yet decomposed.</strong> A CE gets implemented under NEC4 clause 65, adding £450K to the target. The commercial team knows the total, but hasn't yet broken the work into packages with schedules, EVTs, and assigned CAMs. That £450K sits as UB until they do.</p><p><strong>2. Early-stage scope not yet planned.</strong> On a phased programme, later phases might have approved budgets but the detailed planning hasn't started. The budget is real but the work breakdown doesn't exist yet.</p><p><strong>3. Contract changes pending detailed breakdown.</strong> A variation order on a JCT contract or a client instruction on NEC4 adds scope and budget, but the team needs time to plan the delivery.</p><h2 id="worked-example-ce-creates-ub-on-a-rail-package">Worked Example: CE Creates UB on a Rail Package</h2><span class="ge-worked-label">Worked Example</span><div class="ge-callout ge-anim"><p><strong>Scenario:</strong> A £25M NEC4 Option C rail electrification package in the East Midlands. The project is 6 months in. The PMB was originally £25M, with all budget distributed across 14 control accounts.</p><p>On 15 March 2026, compensation event CE-022 is implemented: additional overhead line equipment (OLE) foundations due to unforeseen ground conditions. The assessed value is £450K.</p><p><strong>Immediately after CE implementation:</strong></p><div class="ge-table-wrap ge-anim"><table class="ge-table"><thead><tr><th>Component</th><th>Before CE-022</th><th>After CE-022</th></tr></thead><tbody><tr><td>Distributed CA budgets</td><td>£25,000,000</td><td>£25,000,000</td></tr><tr><td>Undistributed Budget</td><td>£0</td><td>£450,000</td></tr><tr><td><strong>PMB</strong></td><td><strong>£25,000,000</strong></td><td><strong>£25,450,000</strong></td></tr><tr><td>Management Reserve</td><td>£1,200,000</td><td>£1,200,000</td></tr><tr><td><strong>CBB</strong></td><td><strong>£26,200,000</strong></td><td><strong>£26,650,000</strong></td></tr></tbody></table></div><p>The commercial manager needs 2 weeks to decompose the £450K. She breaks it down as follows:</p><ul><li>CA-003 (Foundations): +£280,000 for additional piling and concrete</li><li>CA-007 (OLE Installation): +£120,000 for extended installation programme</li><li>CA-012 (Preliminaries): +£50,000 for 3 extra weeks of site supervision</li></ul><p><strong>After distribution (29 March 2026):</strong></p><div class="ge-table-wrap ge-anim"><table class="ge-table"><thead><tr><th>Component</th><th>Value</th></tr></thead><tbody><tr><td>Distributed CA budgets</td><td>£25,450,000</td></tr><tr><td>Undistributed Budget</td><td>£0</td></tr><tr><td><strong>PMB</strong></td><td><strong>£25,450,000</strong></td></tr></tbody></table></div><p>UB returns to zero. The money has been assigned to people who can manage it and measure <a href="/en/earned-value/definitions/earned-value">earned value</a> against it.</p></div><h2 id="why-ub-matters">Why UB Matters</h2><p>UB matters for one simple reason: you can't measure earned value against it.</p><p>Until budget moves from UB into a control account, no CAM is tracking progress against it. No <a href="/en/earned-value/definitions/earned-value">EV</a> is being generated. No <a href="/en/earned-value/definitions/cost-performance-index">CPI</a> or <a href="/en/earned-value/definitions/schedule-performance-index">SPI</a> is being calculated. The work might be happening on site, costs might be accruing against it, but your EVM system is blind to it.</p><p>That's dangerous. I've seen projects where £1.2M sat in UB for four months because the commercial team was too busy fighting fires to plan the work packages. Meanwhile, the subcontractor was cracking on with the work, costs were hitting the project, and the <a href="/en/earned-value/definitions/variance-analysis-report">variance analysis report</a> showed a worsening cost position that was partly phantom, caused by costs with no matching EV.</p><h2 id="common-mistakes">Common Mistakes</h2><ol><li><strong>Letting UB grow unchecked.</strong> If UB exceeds 5-10% of PMB, your EVM system is losing visibility. Most <a href="/en/earned-value/definitions/eia-748-standard">EIA-748</a> compliance reviews flag UB above 10% as a finding. Set a target: distribute UB within 4 weeks of authorisation.</li><li><strong>Confusing UB with Management Reserve.</strong> MR is for unknown risks. UB is for known scope that hasn't been planned yet. Using MR as a parking spot for budget you haven't bothered to distribute defeats the purpose of both.</li><li><strong>Forgetting to update the PMB when distributing UB.</strong> When UB moves into control accounts, the PMB total stays the same but the composition changes. Some teams accidentally double-count by adding UB to existing CA budgets without reducing UB. Check the equation: PMB should always equal distributed budgets plus UB.</li><li><strong>Not tracking UB ageing.</strong> Fresh UB from last week's CE? Fine. UB from three months ago? That's a planning failure. Track how long each UB item has been undistributed and escalate anything over 4 weeks.</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>What's the difference between Undistributed Budget and Management Reserve?</h3><p>UB is inside the PMB and represents approved scope that hasn't been broken down yet. Management Reserve is outside the PMB and covers risks that haven't materialised. When MR is used, it moves into the PMB (either directly to a control account or briefly through UB). When UB is distributed, it moves from the UB line to specific control accounts within the PMB. The PMB total only changes when MR is added to it.</p><h3>How much Undistributed Budget is acceptable?</h3><p>There's no hard rule, but most EVM practitioners and <a href="/en/earned-value/definitions/eia-748-standard">EIA-748</a> compliance reviewers get uncomfortable above 10% of PMB. On UK construction projects, I'd say keep it under 5% and aim for zero. The whole point of EVM is measuring progress, and you can't measure what you haven't planned.</p><h3>Can work start before UB is distributed?</h3><p>Yes, and it often does. That's part of the problem. The subcontractor doesn't wait for your EVM system to catch up. They start the additional foundations on Monday whether you've created work packages or not. Your job is to distribute UB fast enough that costs and progress are both tracked from day one. If costs accrue against work with no EV baseline, your <a href="/en/earned-value/cost-schedule-variance">cost variance</a> will look worse than reality.</p><h3>Does UB appear on the S-curve?</h3><p>Not directly. UB isn't scheduled, so it doesn't appear on the <a href="/en/earned-value/definitions/planned-value">planned value</a> curve until it's distributed to control accounts and time-phased. Once distributed, the PV curve adjusts upward to reflect the additional planned work. This is another reason to distribute quickly, your <a href="/en/earned-value/s-curve-tracking">S-curve</a> is incomplete until UB hits zero.</p></article></div>