What Is Remaining Budget in EVM? BAC Minus EV Explained

<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="#the-three-way-split">The Three-Way Split</a></li><li><a href="#why-remaining-budget-alone-is-misleading">Why Remaining Budget Alone Is Misleading</a></li><li><a href="#worked-example-bac-12m-the-numbers-dont-add-up">Worked Example: BAC = £12M, the Numbers Don't Add Up</a></li><li><a href="#remaining-budget-vs-etc-vs-work-remaining">Remaining Budget vs ETC vs Work Remaining</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>Remaining Budget is the money you haven't spent yet. That's it. <a href="/en/earned-value/definitions/budget-at-completion">BAC</a> minus <a href="/en/earned-value/definitions/actual-cost">AC</a>. And yet it's one of the most misunderstood metrics in <a href="/en/earned-value">earned value management</a> because people confuse it with two other things: Work Remaining and <a href="/en/earned-value/definitions/estimate-to-complete">Estimate to Complete</a>. They're not the same. Not even close. </p><p>Remaining Budget is part of the <a href="/en/earned-value/definitions">earned value definitions glossary</a>. For the full formula reference, see the <a href="/en/earned-value/formulas">earned value formulas page</a>. </p><h2 id="the-definition">The Definition</h2><p><strong>Remaining Budget = BAC - AC</strong></p><p>That's the budget not yet spent. If your <a href="/en/earned-value/definitions/budget-at-completion">BAC</a> is £12M and you've spent £4.5M, your Remaining Budget is £7.5M. Simple arithmetic. </p><p>But here's the question that actually matters: is £7.5M enough to finish the job? </p><p>To answer that, you need to compare Remaining Budget against two other figures: </p><ul><li><strong>Work Remaining (BAC - EV):</strong> the budgeted cost of work you haven't completed yet</li><li><strong><a href="/en/earned-value/definitions/estimate-to-complete">ETC</a>:</strong> what you actually expect to spend to finish the remaining work</li></ul><p>If Remaining Budget is greater than both, you're in good shape. If it isn't, you've got a problem. And the size of the gap tells you exactly how big that problem is. </p><h2 id="the-three-way-split">The Three-Way Split</h2><p>This is where Remaining Budget gets interesting, and where most teams lose the plot. </p><pre class="ge-ascii-diagram ge-anim"> THE THREE FIGURES THAT TELL THE REAL STORY ========================================== Total Budget (BAC) = £12,000,000 ┌──────────────────────────────────────────────────────────┐ │ │ │ ┌──────────────────┐ ┌──────────────────────────────┐ │ │ │ SPENT (AC) │ │ REMAINING BUDGET │ │ │ │ £4,500,000 │ │ BAC - AC = £7,500,000 │ │ │ │ │ │ │ │ │ └──────────────────┘ └──────────────────────────────┘ │ │ │ └──────────────────────────────────────────────────────────┘ ┌──────────────────────────────────────────────────────────┐ │ │ │ ┌──────────────┐ ┌──────────────────────────────────┐ │ │ │ EARNED (EV) │ │ WORK REMAINING │ │ │ │ £3,800,000 │ │ BAC - EV = £8,200,000 │ │ │ │ │ │ │ │ │ └──────────────┘ └──────────────────────────────────┘ │ │ │ └──────────────────────────────────────────────────────────┘ THE PROBLEM: Remaining Budget = £7,500,000 (money left) Work Remaining = £8,200,000 (budgeted value of work left) GAP = -£700,000 You've spent £4.5M but only earned £3.8M of value. You have £7.5M left to deliver £8.2M of work. At current performance (CPI = 0.844), you'll actually need £8.2M / 0.844 = £9,716,000 to finish. ETC (realistic) = £9,716,000 Remaining Budget = £7,500,000 SHORTFALL = £2,216,000 </pre><p>That diagram tells the full story. Remaining Budget says "we have £7.5M left." Work Remaining says "the remaining scope is budgeted at £8.2M." And the realistic <a href="/en/earned-value/definitions/estimate-to-complete">ETC</a> says "at current efficiency, we'll actually spend £9.7M to finish." Three numbers, three different answers, one very uncomfortable conversation. </p><h2 id="why-remaining-budget-alone-is-misleading">Why Remaining Budget Alone Is Misleading</h2><p>Remaining Budget is a fact. You have £7.5M left in the approved budget. Nobody can argue with that. </p><p>But it tells you nothing about whether that money is enough. It's like checking your bank balance without looking at your upcoming bills. You might have £3,000 in the account. Feels comfortable. Until you remember the £4,200 of invoices due next week. </p><p>On every project I've worked on where the team only tracked Remaining Budget, they were blindsided by the final account. "But we had plenty of budget left at month 9!" Yes, you did. You also had a CPI of 0.85, which meant you needed 18% more budget than you had. The Remaining Budget number was technically correct and practically useless on its own. </p><h2 id="worked-example-bac-12m-the-numbers-dont-add-up">Worked Example: BAC = £12M, the Numbers Don't Add Up</h2><span class="ge-worked-label">Worked Example</span><div class="ge-callout ge-anim"><p><strong>Scenario:</strong> A £12M NEC4 Option C bridge strengthening in South Wales. At the month 8 assessment (28 March 2025), the commercial team reviews the EVM position.</p><br><div class="ge-table-wrap ge-anim"><table class="ge-table"><thead><tr><th>Metric</th><th>Value</th></tr></thead><tbody><tr><td>BAC</td><td>£12,000,000</td></tr><tr><td>AC</td><td>£4,500,000</td></tr><tr><td>EV</td><td>£3,800,000</td></tr><tr><td>PV</td><td>£4,800,000</td></tr></tbody></table></div><br><p><strong>Remaining Budget:</strong> £12,000,000 - £4,500,000 = <strong>£7,500,000</strong></p><br><p>Looks fine. Over 60% of the budget remaining.</p><br><p><strong>But dig deeper:</strong></p><br><div class="ge-table-wrap ge-anim"><table class="ge-table"><thead><tr><th>Derived Metric</th><th>Calculation</th><th>Value</th><th>Signal</th></tr></thead><tbody><tr><td>CPI</td><td>EV / AC</td><td>£3.8M / £4.5M</td><td><strong>0.844</strong>: spending £1.18 per £1 of value</td></tr><tr><td>SPI</td><td>EV / PV</td><td>£3.8M / £4.8M</td><td><strong>0.792</strong>: 21% behind programme</td></tr><tr><td>Work Remaining</td><td>BAC - EV</td><td>£12M - £3.8M</td><td><strong>£8,200,000</strong>: more work left than budget</td></tr><tr><td>ETC (at current CPI)</td><td>Work Remaining / CPI</td><td>£8.2M / 0.844</td><td><strong>£9,716,000</strong>: realistic cost to finish</td></tr><tr><td><a href="/en/earned-value/definitions/estimate-at-completion">EAC</a></td><td>AC + ETC</td><td>£4.5M + £9.716M</td><td><strong>£14,216,000</strong>: forecast outturn</td></tr><tr><td>Forecast overrun</td><td>EAC - BAC</td><td>£14.216M - £12M</td><td><strong>£2,216,000</strong>: if performance doesn't improve</td></tr></tbody></table></div><br><p>The Remaining Budget of £7.5M is a fact. But the project needs £9.7M to finish at current performance. There's a £2.2M shortfall hiding behind a number that looks comfortable.</p><br><p><strong>What the team should do:</strong></p><p>1. Report Remaining Budget alongside ETC in every monthly report</p><p>2. Flag the £2.2M gap to the project sponsor</p><p>3. Develop a recovery plan targeting CPI improvement to at least 0.95</p><p>4. Track the <a href="/en/earned-value/definitions/to-complete-performance-index">TCPI</a>, at this point, TCPI = (£12M - £3.8M) / (£12M - £4.5M) = 1.093. The team needs to perform at 109.3% efficiency for the remaining work to finish on budget. Achievable, but only with specific interventions.</p></div><h2 id="remaining-budget-vs-etc-vs-work-remaining">Remaining Budget vs ETC vs Work Remaining</h2><p>These three get confused constantly. Here's the cheat sheet. </p><div class="ge-table-wrap ge-anim"><table class="ge-table"><thead><tr><th>Metric</th><th>Formula</th><th>What It Tells You</th></tr></thead><tbody><tr><td>Remaining Budget</td><td>BAC - AC</td><td>How much money is left in the approved budget</td></tr><tr><td>Work Remaining</td><td>BAC - EV</td><td>How much budgeted work hasn't been completed yet</td></tr><tr><td><a href="/en/earned-value/definitions/estimate-to-complete">ETC</a></td><td>(BAC - EV) / CPI</td><td>How much you'll actually spend to finish (performance-adjusted)</td></tr></tbody></table></div><p>When CPI = 1.0 (perfect efficiency), all three numbers are different but the story is consistent. When CPI is below 1.0, the gaps widen and the warning signals intensify. When CPI is above 1.0, Remaining Budget is actually more than you need, and the surplus becomes potential gain share on NEC4 Option C. </p><h2 id="common-mistakes">Common Mistakes</h2><p><strong>Reporting Remaining Budget as a health indicator.</strong> "We have 65% of the budget remaining with 60% of the work to do, we're fine." That only works if CPI = 1.0. If CPI is 0.85, you don't have enough budget. Always report Remaining Budget alongside CPI and ETC. </p><p><strong>Confusing Remaining Budget with contingency.</strong> Remaining Budget includes everything: the budget for remaining scope, management reserve, and any allowances. It's not "spare money." It's money allocated to work that hasn't been done yet. </p><p><strong>Not updating BAC after compensation events.</strong> On NEC4 Option C, every implemented CE changes the target and therefore the BAC. If you're calculating Remaining Budget against the original BAC, you're understating it (because the BAC should be higher). This makes the project look worse than it is. Always use the current adjusted BAC. </p><p><strong>Ignoring the ETC comparison.</strong> Remaining Budget on its own is like knowing your fuel gauge reads half-full. Useful. But if you don't know how far you still need to drive, it's not actionable. Always compare Remaining Budget to ETC. </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>Can Remaining Budget be negative?</h3><p>Yes. If AC exceeds BAC, you've already spent more than the total approved budget. On an NEC4 Option C contract, this means your Defined Cost plus fee has exceeded the target total of the Prices. You're now in pain-share territory (or beyond, depending on the share range). A negative Remaining Budget is a genuine crisis that should trigger immediate senior management review. </p><h3>Is Remaining Budget the same as management reserve?</h3><p>No. Management Reserve is a portion of the total budget set aside for unknown risks. Remaining Budget is the difference between BAC and AC. It includes the budgets for all remaining scope, not just contingency. On projects with a formal management reserve, Remaining Budget = remaining scope budget + management reserve (minus any reserve already deployed). </p><h3>How does Remaining Budget relate to cash flow?</h3><p>Remaining Budget tells you about the approved budget. Cash flow tells you about actual payments in and out. On NEC4, the Contractor receives interim payments based on <a href="/en/earned-value/definitions/price-for-work-done-to-date">PWDD</a>, which is Defined Cost plus fee. Cash received might lag behind AC if there are retention deductions or payment delays. So you can have plenty of Remaining Budget but still face a cash flow problem. The two metrics serve different purposes and should be tracked separately. </p></article></div>