Most SAP programs that go sideways had both documents reviewed and approved by the right people. The problem was that the business case made commitments that the project plan had no mechanism to validate, and by the time that gap surfaced, the program was already funded and politically difficult to stop.
What the Business Case Is Actually For
The business case answers one question: why should we do this?
It is an investment justification. It quantifies expected benefits against projected costs over a multi-year horizon, models financial return using NPV, IRR, or payback period, and presents a go/no-go decision point that a CFO or board can act on. The core contents: current state problems in measurable terms, target state KPIs, cost estimates across software, services, and internal resources, and a risk and sensitivity analysis that shows what happens if costs run 20% over or benefits arrive 12 months late.
What the business case does not do: tell you how the transformation gets delivered. That is a different document’s job.
What the Project Plan Is Actually For
The project plan answers one question: how will we do this, and when?
It translates the approved business case into a delivery structure, covering work breakdown, resource model, governance cadence, and phase completion criteria. In SAP programs, this typically follows SAP Activate: Discover, Prepare, Explore, Realize, Deploy, Run. What it must define explicitly: named roles and hours, critical path dependencies, data migration and cutover approach, testing strategy, and go-live criteria.
The project plan is a living document. The business case is usually static. Once approved, the business case becomes the baseline against which the program is measured. The project plan evolves as delivery reveals what the program actually requires.
Where They Come Apart
The sequencing is simple: business case first, project plan second. The relationship between them is often overlooked. Hence, the Business Cases are rarely achieved.
In practice, the two documents are often built by different teams at different times with different assumptions, and the translation between them is rarely explicit. One would think that the benefit projection in the business case would be an explicit acceptance criterion in the project plan. Each one should trace to a workstream, a milestone, and test conditions that confirm whether the system can deliver it. Most programs skip that step. The business case projected a 20% reduction in order-to-cash cycle time. The project plan allocated eight weeks for process design in that area. Nobody knew what that goal was because it wasn’t linked to the plan. That gap was invisible until the Realize phase, when someone mentioned it, and the team ran out of time. If that traceability does not exist between the two documents, how does it become a reality?
The Problem Both Documents Share
Both the business case and the project plan are built on assumptions about a system that does not exist yet. The business case models what the configured SAP system will do. The project plan estimates what configuration will be required. Neither can be tested until the build phase starts, which in a traditional program means months into the engagement, after capital is committed and expectations are set. It is why SAP transformation programs discover problems too late and why making a program governable before you commit capital matters more than most planning processes account for.
That is the planning gap that causes the most damage. Not missing documents, but paper assumptions that have never been tested against a real system. The only thing that closes it is seeing the system and a digital twin before you commit to the benefits.
LeapGreat produces a working version of your SAP S/4HANA system, built on your data and your processes, within one week of your initial requirements session. Before you sign a contract. The benefit projections in your business case become testable in week one, not month six. The timeline estimates in your project plan get grounded in what your actual configuration requires.
The anchor connecting the business case and the project plan is in the digital twin of your future. That way, you have a chance to achieve the business case.
Schedule a call with LeapGreat and see your working system in one week.
