What Is Total Allocated Budget (TAB) 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-formula">The Formula</a></li><li><a href="#the-diagram">The Diagram</a></li><li><a href="#why-tab-matters">Why TAB Matters</a></li><li><a href="#tab-on-nec4-contracts">TAB on NEC4 Contracts</a></li><li><a href="#worked-example-50m-rail-depot-programme">Worked Example: £50M Rail Depot Programme</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>Total Allocated Budget (TAB) is the entire budget for a project: the performance measurement baseline plus management reserve. It's the total pot of money. Not the target. Not the forecast. The actual budget the organisation has allocated to deliver this project from start to finish. On a £50M infrastructure programme, TAB is £50M. The <a href="/en/earned-value/definitions/budget-at-completion">BAC</a> (Performance Measurement Baseline) might be £47.5M, with a £2.5M management reserve held back for unknown risks. Together, they're the TAB.</p><p>TAB is part of the <a href="/en/earned-value/definitions">earned value definitions glossary</a>. For how the baseline budget flows through every EVM formula, see the <a href="/en/earned-value/formulas">earned value formulas page</a>.</p><h2 id="the-formula">The Formula</h2><div class="ge-formula-box ge-anim"><span class="ge-formula-label">Formula</span><code>TAB = PMB + Management Reserve</code></div><p>Where:</p><ul><li><strong>PMB (Performance Measurement Baseline)</strong> = the time-phased budget plan against which performance is measured. This is your <a href="/en/earned-value/definitions/budget-at-completion">BAC</a>.</li><li><strong>Management Reserve (MR)</strong> = budget held outside the baseline for unknown unknowns. Not allocated to specific work packages. Released by management decision when new risks materialise.</li></ul><p>TAB should equal the Contract Budget Base (CBB) at the start of the project. If someone's allocated more or less than the contract value, something's wrong.</p><h2 id="the-diagram">The Diagram</h2><pre class="ge-ascii-diagram ge-anim">TAB: Budget Hierarchy ====================== ┌─────────────────────────────────────────────────┐ │ TOTAL ALLOCATED BUDGET │ │ TAB = £50.0M │ │ │ │ ┌───────────────────────────┐ ┌─────────────┐ │ │ │ PERFORMANCE MEASUREMENT │ │ MANAGEMENT │ │ │ │ BASELINE (PMB) │ │ RESERVE │ │ │ │ BAC = £47.5M │ │ MR = £2.5M │ │ │ │ │ │ │ │ │ │ ┌──────────┬──────────┐ │ │ Not in the │ │ │ │ │ Control │ Control │ │ │ baseline. │ │ │ │ │ Account │ Account │ │ │ Released by │ │ │ │ │ 1 │ 2 │ │ │ PM decision │ │ │ │ │ £12.3M │ £8.7M │ │ │ for unknown │ │ │ │ ├──────────┼──────────┤ │ │ risks. │ │ │ │ │ Control │ Undist- │ │ │ │ │ │ │ │ Account │ ributed │ │ │ │ │ │ │ │ 3-N │ Budget │ │ │ │ │ │ │ │ £24.5M │ £2.0M │ │ │ │ │ │ │ └──────────┴──────────┘ │ │ │ │ │ └───────────────────────────┘ └─────────────┘ │ │ │ │ EVM measures against PMB │ │ MR sits outside measurement │ │ TAB = total organisational commitment │ └─────────────────────────────────────────────────┘ When MR is released: MR decreases → PMB (BAC) increases → TAB stays the same £2.5M → £1.8M £47.5M → £48.2M Still £50.0M</pre><p>The key thing: when management reserve is released into the baseline, TAB doesn't change. The money moves from MR to PMB. Total stays constant. This is a fundamental principle that keeps the budget honest.</p><h2 id="why-tab-matters">Why TAB Matters</h2><p>TAB exists to answer one question: "How much money has the organisation committed to this project?" It sounds trivially simple. It isn't.</p><p>On large programmes, budget gets scattered. There's the contract value. There's the management reserve. There's contingency held at programme level. There's risk money sitting in the sponsor's budget. Nobody knows the total. TAB forces clarity. One number. Everything included.</p><p>I've been in quarterly reviews where the project team reports <a href="/en/earned-value/definitions/estimate-at-completion">EAC</a> of £52M against a BAC of £47.5M and everyone panics about the £4.5M overrun. But TAB is £50M. The management reserve covers £2.5M of it. The real exposure is £2M, not £4.5M. Without TAB in the picture, the wrong conversation happens.</p><h2 id="tab-on-nec4-contracts">TAB on NEC4 Contracts</h2><p>On NEC4 Option C, TAB maps roughly to the total of the Prices plus any Client risk reserve:</p><div class="ge-table-wrap ge-anim"><table class="ge-table"><thead><tr><th>Component</th><th>NEC4 Equivalent</th><th>Amount</th></tr></thead><tbody><tr><td>PMB (BAC)</td><td>Target total of the Prices</td><td>£47,500,000</td></tr><tr><td>Management Reserve</td><td>Client's risk allowance (outside contract)</td><td>£2,500,000</td></tr><tr><td><strong>TAB</strong></td><td><strong>Total project budget</strong></td><td><strong>£50,000,000</strong></td></tr></tbody></table></div><p>When compensation events are implemented, the target (BAC) increases. If that increase comes from the management reserve, TAB stays the same. If the CEs exceed the management reserve, TAB needs to increase. That requires a formal budget approval. The moment TAB needs to increase is the moment someone needs to go to the board and ask for more money.</p><h2 id="worked-example-50m-rail-depot-programme">Worked Example: £50M Rail Depot Programme</h2><span class="ge-worked-label">Worked Example</span><div class="ge-callout ge-anim"><p><strong>Scenario:</strong> A £50M NEC4 Option C rolling stock maintenance depot. The budget structure at contract award in July 2025:</p><ul><li><strong>TAB</strong> = £50,000,000</li><li><strong>PMB (BAC)</strong> = £47,500,000 (target total of the Prices)</li><li><strong>Management Reserve</strong> = £2,500,000 (5% held by the Client project sponsor)</li></ul><p><strong>Month 6 (January 2026):</strong> Two compensation events are implemented:</p><ul><li>CE-001: Ground stabilisation (clause 60.1(12)) = +£680,000</li><li>CE-002: Additional fire suppression (clause 60.1(1)) = +£420,000</li><li>Total CE adjustment: +£1,100,000</li></ul><p>The Client releases £1.1M from management reserve into the target:</p><ul><li><strong>Revised BAC</strong> = £47,500,000 + £1,100,000 = <strong>£48,600,000</strong></li><li><strong>Remaining MR</strong> = £2,500,000 - £1,100,000 = <strong>£1,400,000</strong></li><li><strong>TAB</strong> = £48,600,000 + £1,400,000 = <strong>£50,000,000</strong> (unchanged)</li></ul><p><strong>Month 14 (September 2026):</strong> Three more CEs are implemented totalling £1,800,000. But only £1,400,000 remains in MR.</p><ul><li>MR exhausted: £1,400,000 released to BAC</li><li>Unfunded CEs: £400,000 requires additional budget approval</li><li><strong>Revised BAC</strong> = £48,600,000 + £1,800,000 = <strong>£50,400,000</strong></li><li><strong>MR</strong> = <strong>£0</strong></li><li><strong>New TAB</strong> = £50,400,000 + £0 = <strong>£50,400,000</strong></li></ul><p>TAB just broke through the original £50M. That's the trigger for the project sponsor to escalate to the investment board. The conversation isn't "we might need more money." It's "TAB has increased by £400K and we have zero management reserve remaining for the last 10 months of the project."</p></div><p>That's the power of tracking TAB. It gives the board an early warning before the budget spirals.</p><h2 id="common-mistakes">Common Mistakes</h2><ol><li><strong>Confusing TAB with BAC.</strong> BAC is the performance baseline. TAB includes BAC plus management reserve. When someone says "the budget is £50M," ask which one they mean. On one programme I worked on, the project team was reporting BAC as the budget while the sponsor was tracking TAB. They were £3M apart and neither knew why.</li><li><strong>Not tracking MR drawdown.</strong> Every time management reserve is released, record it. Date, amount, reason, authorisation. If MR is depleting faster than planned, the project is consuming its safety margin. Plot MR remaining against elapsed time. If MR is half gone at 30% completion, that's a problem.</li><li><strong>Allowing TAB to creep without governance.</strong> TAB should only change through a formal process: board approval for additional budget. If TAB increases every month without scrutiny, it defeats the purpose. The whole point is to make budget increases visible and painful.</li><li><strong>Forgetting undistributed budget.</strong> Within the PMB, there's often an undistributed budget (UB) that's been approved but not yet assigned to control accounts. This is different from management reserve. UB is inside the baseline; MR is outside. Mixing them up distorts your EVM reporting.</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 TAB and the contract value?</h3><p>At contract award, TAB should equal the contract value (or the total project budget including any client-held reserves). Over the project life, the contract value adjusts with compensation events or variations, and TAB adjusts to match. If TAB exceeds the original contract value, additional funding has been committed.</p><h3>Can management reserve be returned if not used?</h3><p>Yes. If the project completes without needing the full MR, the unused portion returns to the organisation. That's a good outcome. It means the risks didn't materialise or were managed within the baseline. On NEC4 Option C, unused MR is simply budget the Client never needed to release.</p><h3>How much management reserve is typical?</h3><p>Between 3% and 10% of PMB, depending on project complexity and risk profile. A straightforward building project might carry 3-5%. A complex rail or nuclear project might carry 8-10%. The right amount comes from a quantified risk assessment, not a rule of thumb. But 5% is a reasonable starting point if you haven't done the maths.</p><h3>Does TAB appear in standard EVM reports?</h3><p>It should. The ANSI/EIA-748 standard includes TAB in the Contract Performance Report (CPR) Format 1. In practice, many project teams only report BAC and EAC, which leaves the management reserve invisible. I'd always recommend showing TAB, BAC, MR remaining, and MR consumed on the monthly dashboard.</p></article></div>