Are You Under-Budgeting and Under-Planning Your SAP ECC-to-S/4 Transition? 

Migrating off SAP ECC and on to S/4HANA in the near future? SAP maintenance of ECC is sunsetting in 2027, with some support available into 2030. Don’t underestimate the time and complexity involved.  

Most organizations materially under-budget and under-plan their S/4HANA transformations because they anchor on software and system integrator costs while underestimating internal effort, data complexity, and operating model change. Now’s the time to set up your organization for success and lay the foundation for an efficient, profitable transition. 

Here’s where to begin. 

Phase 1: Strategic Planning, Project Budgeting, and Migration Planning 

Timeline: 3–6 Months 

Goal: Define the “What,” “Where,” and “How Much.” 

1. SAP Readiness Check (Technical Foundation) 

Before you budget, run an SAP Readiness Check. It provides: 

• Simplification items: Which ECC functions are deprecated or changed in S/4HANA. 
• Custom code impact: An automated scan of your custom “Z” objects to identify incompatibilities with S/4HANA and expose embedded technical debt that must be remediated, retired, or redesigned. 
• Sizing recommendations: The HANA memory requirements (this dictates your cloud/hardware costs). 
• Data readiness assessment: Existing database and data structures can have a big implication on the transition timeline, data strategy, and transition options. If data isn’t in a unicode format, doing a Brownfield RISE conversion is more complex compared to a Greenfield GROW conversion where there is no impact. 

2. Architecture Decision and Hosting Model 

Decide between SAP RISE versus GROW. Each has public vs private cloud options and slight functionality differences. From there, various kinds of bundling, licensing, and management options are available.  

Note: With GROW, you can only do Greenfield implementations; with RISE, you can do Greenfield, Brownfield, or Bluefield (see below). 

3. Selection of Migration Strategy (The ‘Big Three’) 

You must choose your path now, as it can change the budget by millions: 

• Greenfield (new implementation): Best if your ECC processes are “broken” or highly customized. Start fresh by adopting “Clean Core” and standard best practices. 
  • Cost profile: Higher upfront consulting; lower long-term maintenance. 
• Brownfield (system conversion): A technical “lift and shift.” Best if your current processes work well, you want to preserve historical data, and you’re under a tight timeline. It’s not ideal, but in certain situations, it’s the most feasible. 
  • Cost profile: Lower upfront; carries over technical debt. 
• Bluefield/selective data transition: Carve out specific data or company codes. 
  • Cost profile: High complexity; requires specialized third-party tools (e.g., SNP or Natuvion). 

4. Budgeting: Beyond the Software 

A common mistake is budgeting only for licenses and the system integrator. Ensure your budget includes: 

• Backfill costs: Budgeting for temporary staff to cover the “day jobs” of your SMEs while they work on the project. 
• Data cleansing: SAP won’t fix your “bad data.” You may need a dedicated data project before the migration starts. 
• Third-party integrations: Budget for updating tax engines (Vertex/Avalara), EDI, and WMS systems. 

Phase 2: Implementation Planning and Resource Allocation 

Timeline: 2–4 Months 

Goal: Define the “Who” and “When.” 

1. Assembling the Dream Team 

You cannot rely solely on external consultants. Your internal team must include: 

• Executive sponsor: A C-suite leader who can break ties when departments disagree on process changes. 
• Process owners (SMEs): Your best people from finance, supply chain, and sales. If they aren’t “too busy” to be on the project, they probably aren’t the right people. 
• Global process leads: Empowered individuals who can authorize moving from “custom” back to “SAP Standard.” 
• Project Management Office (PMO): A PMO is a critical cross-functional team that can design and enforce a governance model and manage the execution of tasks, resources, deadlines, budgets, and change. An implementation is not just an IT project; it’s an integrated business transformation. A PMO can help remove blockers, secure approvals, and streamline global versus local decisions. 

2. System Integrator Selection 

Don’t just pick the lowest bidder. Evaluate partners based on: 

• Conversion experience: Ask for references specifically for ECC to S/4 migrations, not just Greenfield builds. 
• Accelerators: Do they have proprietary tools to automate custom code remediation or data transformation? 

3. The ‘N+1’ Landscape Strategy 

Planning your environments is a major cost and resource driver. 

• Project landscape: You will need a sandbox, development, and QA environment for the S/4 project. 
• Maintenance landscape: You still need to support your existing ECC system for 18 months. 
• Strategy: Define how you will “double-maintain” (dual entry) transports between the old ECC world and the new S/4 project. 

4. Data Purging and Archiving (The ‘Weight Loss’ Phase) 

HANA is memory-intensive. 

• Action: Implement an archiving strategy now. Identify “cold data” (7+ years old) that can be moved to a low-cost archive rather than the high-performance HANA database. This can reduce your infrastructure costs by 20–40%. It’s important to note that this action introduces its own level of cutover complexity. 

5. Change Management Strategy 

S/4HANA introduces the Fiori UI, which is a radical departure from the “Blue Screens” of ECC. 

• Planning: Budget for a dedicated change management lead. This isn’t just training; it’s the strategy for how you will convince users that a new way of working is better, preventing shadow IT and resistance. 

With the 2027 deadline fast approaching, your migration strategy should be a top priority. For expert planning, support, and implementation advisory, contact CrossCountry Consulting.