The numbers don’t make for comfortable reading. More than 60% of SAP migrations exceed budget, only 8% complete on schedule, and 65% of organisations that reach go-live report significant quality deficiencies on the other side. That’s from Horvath Partners‘ “Business Transformation Unlocked” study — a survey of 200-plus executives at SAP-using companies.
ISG’s 2026 “State of SAP Migrations” report surveyed 200 senior decision-makers at large global companies and landed in nearly the same place — close to 60% falling behind schedule and budget. Two independent research bodies. Similar conclusions. That’s not noise, it’s a pattern.
This is the typical experience across roughly 35,000 SAP ECC customers facing a 2027 end-of-mainstream-maintenance deadline. This article is part of our complete guide to SAP ECC end of support and what comes next, which covers that broader context in detail. What most migration content glosses over is the specific failure mechanisms behind these statistics — and what failure actually looks like at mid-market scale. This article names those mechanisms directly, and works through realistic project costs for organisations with 50–500 employees using the only publicly disclosed enterprise cost data available.
Why do 60% of SAP migrations exceed budget and only 8% complete on schedule?
The Horvath study (reported by CIO.com) found that budgets were blown severely in one quarter of migrations and moderately in another 40% — the 60% figure is a composite of both. Schedules fared even worse: only 8% finished on time, and the average project ran 30% longer than planned.
ISG’s independent survey reached almost the same conclusion from a completely different sample. The convergence matters. Horvath is a German management consultancy. ISG is a technology research and advisory firm with no systems integration business — no financial incentive to overstate the problem. When two research bodies with no relationship to each other land on similar figures, the statistics are defensible.
Christian Daxböck, study director and Horvath partner, put it plainly: “This mismatch leads to the enormous discrepancies between plan and results.” The mismatch is between how organisations assess their own complexity and what they actually encounter once the project is underway. Both surveys cover large enterprises with 1,000-plus employees — which matters, because mid-market organisations face proportionally similar failure causes with fewer resources to absorb the consequences. For context on what the 2027 end-of-mainstream-maintenance deadline actually means and which ECC customers are affected, that context is covered separately.
Why does the most common SAP migration approach also have the worst outcome record?
ISG’s data shows that only 18% of organisations implement new business processes when migrating to S/4HANA. Nearly half — 49% — carry their existing processes over unchanged. That tells you a lot about why brownfield migration is popular, and why the outcome data for it is so problematic.
Brownfield migration (system conversion) takes your existing ECC configuration, customisations, and historical data and moves them directly into S/4HANA. Less immediate disruption, shorter timelines, easier stakeholder buy-in. The catch is that it also carries forward every ABAP customisation your organisation has accumulated over the past decade or two — all of the technical debt, unresolved. Those 49% who carry legacy processes unchanged aren’t streamlining their business. They’re reconstituting their customisation burden in the new system.
Greenfield migration — a clean S/4HANA implementation requiring full business process redesign — eliminates that debt, but at a cost: higher upfront investment and a longer timeline that most mid-market organisations find hard to justify. Selective data transition offers a middle path, migrating selected processes or data subsets, but it’s underrepresented in outcome data and requires careful scoping. Choosing between these approaches is one of the highest-stakes decisions in the migration process. As Stanton Jones, ISG analyst, noted: “To fully leverage the potential of automation, analytics, and AI, companies must be prepared to make fundamental changes in governance, data quality, and process standardisation.”
What is Phase Zero in an SAP migration and why does skipping it explain most failures?
Phase Zero is the structured preparation stage that happens before formal project kickoff — equivalent to the Discover phase in SAP’s Activate methodology. It defines what the project covers and what “done” looks like before you sign anything with a systems integrator.
In practice, Phase Zero produces five deliverables: a detailed business case, a target operating model, a solution architecture blueprint, a change management plan, and a data and integration strategy. ISG identifies weak governance — not technical challenges — as the primary cause of migration delays. Phase Zero is where governance structures, decision-making rights, and SI accountability mechanisms get established.
When Phase Zero gets compressed — and it does get compressed, because it’s not billable SI work and nobody wants to delay the “real” project start — scope enters execution unresolved. Data quality problems that could have been mapped before kickoff become unplanned cost items in month seven. The Horvath survey makes the failure pattern concrete: top challenges cited included lack of IT integration perspective (28%), insufficiently defined processes (24%), and lack of knowledge about third-party systems (23%). Phase Zero failures, all of them, showing up as execution problems.
How does ABAP customisation debt turn a technical upgrade into a budget crisis?
ABAP (Advanced Business Application Programming) is SAP’s proprietary language for customising and extending ECC functionality. Over a typical 10–20 year ECC deployment, organisations accumulate thousands of custom programmes, modifications, and enhancements — bespoke reports, workflow extensions, interface adaptors, workarounds for processes that didn’t fit standard SAP behaviour. All of it works in ECC. None of it is automatically compatible with S/4HANA.
Custom code is described as “the single biggest risk factor in any SAP transformation” by SmartShift, a firm specialising in automated ABAP remediation. Every custom programme must be inventoried, tested for compatibility, and either refactored, retired, or replaced with standard S/4HANA functionality. Many organisations don’t have an accurate inventory — documentation is outdated, usage tracking is nonexistent, and nobody is quite sure what’s actually running in production.
The failure mechanism follows a consistent sequence: undiscovered ABAP debt surfaces during execution, late-stage scope expansion is required, costs and timeline blow out. Horvath’s research names scope expansion as the main reason for overruns, ahead of suboptimal project delivery and poorly managed data transition. The scope expansion isn’t random. It’s the inventory you didn’t complete in Phase Zero, presenting its bill.
How does scope creep in SAP migrations turn initial estimates into fiction?
Scope creep is the mechanism that connects Phase Zero neglect and undiscovered ABAP debt to the budget and schedule overruns in the Horvath and ISG data. Four drivers compound each other during execution.
Undiscovered ABAP customisations surface once code analysis actually begins — scope additions that were never in the original plan. Data quality problems not assessed in Phase Zero require remediation work that’s now on the critical path. Business stakeholders who see the new system for the first time start adding requirements. Integration failures with third-party systems that weren’t fully mapped generate unplanned work that pushes go-live.
ISG’s Stacey Cadigan is direct about the governance dimension: “Many migration programmes involve multiple system integrators, SAP service providers, and niche specialists — there is a lack of clear decision-making rights, acceptance criteria, and responsibilities between providers.” Without those structures, every new discovery becomes a renegotiation rather than a controlled scope decision.
ISG recommends linking part of providers’ compensation to specific delivery metrics — data migration completeness, integration test stability, cutover sample success — to align incentives from the start. Building a defensible business case starts with understanding how scope expands before it starts.
What does an SAP migration actually cost at mid-market scale?
Before the numbers: what follows is an analytical model, not empirical data. No publicly available peer-reviewed cost data exists for mid-market SAP migrations. The figures below are derived from enterprise-scale disclosures and published implementation benchmarks, with stated assumptions. Use them for planning and contingency modelling, not contract negotiations.
The only publicly disclosed enterprise-level migration cost comes from Halliburton (NYSE: HAL), a Fortune 50 global oilfield services company. Their Q4 2025 investor relations disclosure reported $42 million in SAP S/4 migration costs for that quarter alone. Halliburton is an extreme upper bound — decades of ECC customisation, a complex global operational environment, and a scale of integration work with no direct parallel in a 200-person technology company.
Published benchmarks suggest implementation costs of $1,000–$3,000 per named SAP user for mid-market projects, with data migration adding 15–25% of implementation cost on top. Working from those benchmarks:
50–100 employees (30–60 SAP users): total project cost in the range of $300,000–$900,000
100–250 employees (60–150 SAP users): total project cost in the range of $800,000–$2.5 million
250–500 employees (150–300 SAP users): total project cost in the range of $2 million–$6 million
These ranges assume adequate Phase Zero investment. If Phase Zero gets compressed, add 20–40% to the upper bound of each range — that’s the contingency the 60% over-budget rate from Horvath justifies.
Cost components that many initial estimates miss: implementation services (SI fees), data migration and remediation, infrastructure, internal resource time, training, and a post-go-live remediation reserve. The 65% quality deficiency rate means that reserve isn’t optional — it’s planning for the near-certain. Ninety-five percent of SAP customers say making an ROI case for S/4HANA is difficult or takes significant effort, per a Rimini Street survey of 455 organisations. The total cost of ownership question is harder to answer than most migration content lets on.
What do successful SAP migrations have in common — and what did IBM’s migration require?
IBM completed its S/4HANA migration in July 2024 and reported a 30% reduction in infrastructure-related operational costs. Worth understanding what produced that result — because IBM’s success is not a counterargument to the failure statistics. It’s evidence of what success actually requires.
Four elements appear consistently across successful migrations.
Substantial Phase Zero investment: scope, data quality, and custom code addressed before commitment. A clean core commitment: deliberately minimise ABAP customisations in the new system and accept business process changes rather than technical workarounds. Strong governance: defined scope change processes and SI accountability mechanisms in place from day one. Phased go-live: staged deployment that limits the impact of any single quality defect.
Each element is the structural inverse of a documented failure cause. IBM’s scale is larger than a 200-person technology company, but the structural principles transfer. The preparation investment is what determines how migration approach affects outcomes.
What do the failure statistics mean for your migration decision timeline?
The failure rate data is an input to decision-making, not an argument against migrating. The 2027 end-of-mainstream-maintenance deadline is fixed. With only a minority of SAP ECC customers having fully completed their S/4HANA transition, Horvath’s assessment is that executives “will start to feel the heat” — late starters face compressed Phase Zero timelines and heightened competition for specialist SAP labour.
The data suggests three specific adjustments to how you should frame the decision.
If budget is constrained: the 60% over-budget rate means initial estimates are structurally optimistic. Plan for the upper bound of the cost ranges above, not the midpoint. More than 40% of Horvath respondents said they would increase the budget from the outset given the chance to do it again.
If timeline is constrained: the 8% on-schedule rate means schedule contingency is not a risk mitigation option — it’s a planning requirement. A project starting now with an 18-month estimate has a high probability of landing post-2027 without contingency built in.
If your organisation has significant ABAP customisation debt: a thorough code audit before contract signature is the single most reliable way to improve estimate accuracy. It surfaces scope before it becomes a change order.
The alternative to migrating before the deadline isn’t indefinite ECC operation. SAP’s extended support runs to 2030; Rimini Street extends SAP support until 2040 for customers preferring to stay on ECC. Both carry their own cost and risk profiles. Our complete guide to SAP ECC end of support and what comes next covers those strategic options in detail.
The Horvath and ISG statistics are not a reason to delay. They’re a reason to start Phase Zero now, with adequate budget and the expectation that initial estimates will need revision. Build contingency in from the start rather than discovering the need for it mid-project — that’s what separates the 8% who finish on schedule from the 92% who don’t.
Frequently Asked Questions
How much does an SAP migration really cost for a company with 200 employees?
A 200-employee organisation with approximately 100–120 SAP users can expect a total project cost in the range of $1.2 million–$3.5 million, based on published benchmarks of $1,000–$3,000 per named SAP user for implementation services plus 15–25% for data migration.
That assumes adequate Phase Zero investment. Compress preparation and you should add 20–40% to the upper bound. The cost components include implementation services (SI fees), data migration and remediation, infrastructure, internal resource time, training, and a post-go-live contingency reserve — not just licence fees. No publicly available empirical data exists for mid-market migrations; these figures are derived analytically from enterprise-scale disclosures.
Why is the SAP migration taking so long at most companies?
The 8% on-schedule completion rate reflects three compounding causes. Phase Zero neglect means scope is unresolved at project start. ABAP custom code volumes are consistently underestimated — organisations often don’t know what they have. Governance failures mean scope changes get renegotiated ad hoc rather than controlled through defined processes.
ISG identifies governance failure — unclear decision-making rights and weak SI accountability — as the top cause of project delays, not technical complexity. Horvath Partners found the average SAP S/4HANA implementation takes 30% longer than originally anticipated.
What is Phase Zero in an SAP migration?
Phase Zero is the structured pre-migration preparation stage — equivalent to the Discover phase in SAP’s Activate methodology — conducted before formal project kickoff.
It produces four key deliverables: a data readiness assessment, a custom ABAP code audit, a system landscape map, and defined scope with acceptance criteria. Organisations that invest in Phase Zero consistently outperform those that compress or skip it. ISG identifies weak Phase Zero governance as the leading cause of migration failures.
What is the difference between brownfield and greenfield SAP migration?
Brownfield (system conversion) carries existing ECC configuration, customisations, and historical data into S/4HANA — lower immediate disruption but inherits all ABAP technical debt. Greenfield (new implementation) starts with a clean S/4HANA instance and re-implements business processes from scratch — eliminates ABAP debt but requires full redesign and higher upfront investment. Selective data transition (SDT) is a hybrid approach migrating selected processes or data subsets.
Only 18% of organisations implement new processes during migration per ISG, which explains why brownfield remains the most common choice despite its worse long-term outcome profile.
What is ABAP and why does it matter for SAP migrations?
ABAP (Advanced Business Application Programming) is SAP’s proprietary language for customising and extending ECC functionality. Over years of operation, SAP ECC installations accumulate thousands of custom ABAP programmes that are not automatically compatible with S/4HANA.
Every custom ABAP programme must be inventoried, tested, and either refactored, retired, or replaced with standard S/4HANA functionality — a process that reveals scope larger than initial estimates. Technical debt that isn’t addressed during transformation multiplies and makes future upgrades harder.
Why does data quality cause SAP migration failures?
Poor data quality is the silent killer in SAP migrations — organisations pour effort into technical configuration while data issues slip under the radar until go-live exposes them. Duplicate customer records, incomplete vendor data, and inconsistent financial account structures that look clean on the surface cause operational failures once S/4HANA starts processing them.
Over 90% of data migration projects run over time or budget due to data quality problems, per Gartner figures cited by DataVapte. Master Data Management — building clean “golden records” for core business objects — is the remediation approach, but it requires Phase Zero investment to scope and implement before migration begins.
How does governance failure lead to SAP project overruns?
ISG identifies governance failure as the primary cause of SAP migration delays — not technical complexity, but the organisational structures controlling the project. The specific failures: unclear business ownership of requirements, inability to make binding decisions on scope trade-offs, and absence of contractual accountability mechanisms over systems integrators.
Without defined scope change management processes, each new discovery — undiscovered ABAP debt, data quality problems — becomes an ad-hoc renegotiation rather than a controlled decision. Governance investment is a Phase Zero deliverable: define decision-making rights, scope change thresholds, and SI acceptance criteria before project kickoff, not after the first change order.
