Every conversation about SAP S/4HANA migration starts the same way: “ECC support ends in 2027.” That statement is factually correct. It is also strategically incomplete.
After 250+ SAP transformations, here is what we have learned: the date is not what breaks programs. What breaks them is what happens to organizations that wait until the date feels uncomfortably close — and then make consequential decisions under pressure rather than with clarity.
There is a name for this. It is called decision compression. And it is quietly reshaping the market right now.
When should a large enterprise begin its SAP S/4HANA migration?
A full S/4HANA migration for a large enterprise typically requires 18 to 36 months. Organizations targeting a go-live before the 2027 SAP ECC support deadline need to be in active assessment by mid-2026 at the latest. Starting later does not create a worse migration — it eliminates the option of a well-planned one.
A 2025 Horváth study of 200 SAP user companies found that only 8% of organizations that have completed their S/4HANA migration did so on schedule, with projects taking an average of 30% longer than planned. In more than six out of ten cases, the planned budget was exceeded.
of completed S/4HANA migrations delivered on schedule
average project duration overrun across surveyed firms
of projects exceeded planned budget
The root cause, according to the same research, is not technical failure. The leading reasons are scope expansion during transformation, a poorly managed data transition, a blueprint that gets revised rather than fixed, and a lack of clear governance. These are not technology problems. They are decision problems — and almost all of them are traceable to choices that were made too quickly, too late, or with insufficient clarity about what was actually being decided.
A separate 2026 survey by Precisely and ASUG found that 30% of SAP migration projects are either delayed or over budget — and that is among organizations actively in motion. The ones still in evaluation are facing something more significant: a narrowing window in which the quality of their decision-making is about to matter most.
Decision compression is not a single event. It is a gradual narrowing of options that organizations often do not notice until they are already inside it. It shows up in three consistent patterns.
STAGE 1: TALENT
By 2026, shortages of experienced S/4HANA specialists are affecting most projects, with demand particularly high for data migration, finance, testing, and cutover roles. Demand for S/4HANA talent could reach three times the available supply by 2027, with consulting rates expected to spike in the final year. The best delivery architects — the ones whose experience at the start of a programme determines its outcome — get booked first. Organisations that wait do not get a worse version of the same team. They get a different team entirely.
STAGE 2: COST
Consulting rates are expected to increase by 30–50% in 2026–27 due to surging demand and limited availability of experienced SAP resources. This is not a vendor price increase. It is simple supply and demand — and it disproportionately affects organizations that have deferred the decision, because they are entering the market at the point of highest competition.
STAGE 3: SCOPE
When time pressure increases, the natural response is to simplify. Brownfield is chosen because it sounds conservative. Custom code is carried forward because there is no time to assess it properly. Testing cycles are compressed because go-live dates are fixed. Research by the Prosci Institute found that 75–80% of projects fail due to poor change management stemming from inadequate planning, communication, or stakeholder engagement — and change management is consistently the first workstream to be cut when time runs out.
None of these decisions feel like mistakes when they are made. They feel like pragmatism. They feel like keeping things moving. The cost shows up later — in rework, in post-go-live disruption, and in the erosion of confidence in the program itself.
Across our recent S/4HANA programs, the single most accurate predictor of go-live confidence was not which migration path the client selected. It was how early they engaged in structured process mapping. Organizations that completed a formal landscape assessment before committing to an approach resolved scope disputes in weeks rather than months — and avoided the mid-program blueprint revisions that account for the majority of cost overruns we see in the market.
2026 is the year that determines how 2027 unfolds for most large enterprises.
As of early 2026, legacy SAP ECC use has fallen below 50% of organizations for the first time. But 35% of larger enterprises — those with the most complex landscapes — remain in the planning or exploration phases.
These are precisely the organizations for whom a rushed migration carries the highest risk, and for whom the S/4HANA readiness assessment window is narrowest. A full S/4HANA migration for a large enterprise typically takes 18 to 36 months. That arithmetic is unforgiving. An organization that has not begun a structured assessment by mid-2026 is not choosing between a good migration and a rushed one. It is choosing between a rushed migration and an extended maintenance premium — at added cost — while watching the talent pool it needed become unavailable.
The organizations that navigate this well are not necessarily the ones moving fastest. They are the ones who treated 2026 as a decision window rather than a waiting room. They separated assessment from execution. They made trade-offs consciously, with an understanding of their actual landscape rather than their assumed one. And they retained leverage — with partners, with talent, and with their own internal stakeholders — because they started before pressure forced their hand.
The single highest-value action available to most enterprise SAP leaders in 2026 is not committing to a migration path. It is building the clarity that makes a commitment defensible.
None of this requires a commitment to execute. It requires a commitment to understand. And the organizations that make that commitment now — before the market tightens further, before the best delivery teams are booked, before scope decisions get made by default rather than by design — are the ones that will look back at 2026 as the year they got ahead of this.
The ones that don’t will be the ones saying, months into execution: we should have known this earlier.
What is decision compression in SAP migration?
What is the biggest cause of SAP S/4HANA project failure?
What is included in TSP’s S/4HANA Phase 0 readiness assessment?
How long does an SAP S/4HANA migration take for a large enterprise?
TSP has delivered 250+ SAP transformations across manufacturing, retail, wholesale, life sciences, and agribusiness. Our Phase 0 Sandbox engagement is a $25K, time-boxed exploration designed to give your leadership team the landscape clarity to make a migration decision with confidence — not under pressure.
