Let’s be honest: by now, you’ve probably heard the term “clean core” more times than you can count. At SAP events. In partner meetings. In PowerPoints.
But here’s the issue: everyone talks about it, very few can explain it clearly. Is it a design principle? A toolset? A cloud requirement? A governance headache?
This blog gives you straight answers to the most common questions CIOs, IT managers and enterprise architects ask about SAP’s clean core strategy.
What does “keeping the core clean” actually mean?
It means you don’t modify the standard SAP ERP system, no direct changes to SAP’s core code, tables or data models.
Instead, you handle extensions using SAP’s official extensibility frameworks. That could mean side-by-side apps on SAP BTP, in-app extensibility tools, or APIs and events.
What this looks like in practice:
Con
- Creating custom tables in the SAP database
- Modifying standard SAP programs or function modules
- User exits and enhancement spots that change core behaviour
Pro:
- Building extensions on BTP that connect via APIs
- Using SAP's key user extensibility for form modifications
- Custom apps that read/write via OData services
The idea: your ERP becomes a stable, upgrade-friendly system of record, while custom logic and innovation live next to it, not inside it.
Why is SAP pushing this so hard?
Because SAP is transitioning to a cloud-first model, where continuous updates and innovation are the norm, not the exception.
The business reality: SAP’s cloud strategy depends on being able to push updates frequently without breaking customer implementations. Every custom modification creates a potential failure point that SAP has to account for, or simply can’t support.
Clean Core is the foundation that allows SAP (and you) to move faster, deliver new capabilities regularly, and reduce the cost and effort of maintaining your ERP landscape.
What are the real costs and investments involved?
This is where many organizations get surprised. Clean core isn’t just a technical shift, it’s a significant investment:
Key investments:
- Time: 6-18 months of analysis and remediation work for existing customizations
- Licensing: SAP BTP consumption-based pricing plus potentially additional S/4HANA user licenses
- Skills: New development capabilities in cloud development, API design, BTP platform knowledge
- Migration: Retrofitting existing custom code (typically 30-70% of customizations need rework)
Realistic timeline: Most organizations need 12-24 months to fully transition to clean core, depending on their customization complexity.
Hidden costs: Training existing teams, consultant fees, temporary dual-system maintenance, and possible business process adjustments.
What are the concrete benefits?
The benefits are both technical and strategic:
Technical benefits:
- Faster upgrades , from 6-month projects to quarterly updates
- Lower TCO , 40-60% reduction in maintenance costs after transition
- Cloud readiness , critical for RISE and S/4HANA Cloud
Strategic benefits:
- Business agility, deliver innovation faster using BTP and low-code tools
- Future-proofing, access to SAP's latest capabilities without customization conflicts
- Reduced vendor lock-in, side-by-side extensions can be more easily migrated
Real-world impact: Companies that successfully implement clean core report 50-70% faster time-to-market for new business capabilities and 30-50% reduction in system maintenance overhead.
What are the risks and challenges?
Clean core isn’t plug-and-play. It comes with real challenges:
Organizational challenges:
- Cultural shift from "modify everything" to "standard first, extend smart"
- New skills gap in cloud development, APIs, and SAP BTP
- Need to say no more often to business users expecting fast fixes
Technical risks:
- Performance considerations with API-based integrations vs. direct database access
- Potential functionality gaps where SAP standard doesn't fully match business needs
- Dependency on SAP's roadmap for new extensibility capabilities
Transitions risks:
- Temporary loss of functionality during migration
- Higher costs during transition period before benefits materialize
Some things may take longer up front. But the long-term payoff is worth it: more stability, faster change cycles, and systems that can evolve with your business.
How do we handle our existing customizations?
This is often the most complex part of clean core adoption. You have three main strategies:
Retire: Eliminate customizations that no longer add value
- Audit usage: many customizations are rarely used
- Challenge business necessity: processes may have changed
- Typically 20-40% of customizations can be retired
Retrofit: Convert existing customizations to clean core patterns
- Move custom logic to BTP side-by-side applications
- Replace direct database access with API calls
- Use SAP's migration tools where available
Rebuild: Recreate functionality using modern approaches
- Leverage improved S/4HANA standard functionality
- Use SAP's low-code/no-code tools for simpler customizations
- Build cloud-native solutions for complex requirements
Practical approach: Start with a comprehensive custom code scan, then categorize by business criticality and technical complexity to prioritize your approach.
What role does SAP BTP play in this?
A central one. SAP BTP is where your customizations go when you commit to a clean core.
Key BTP capabilities for clean core:
- Side-by-side extensibility: Build applications that interact with SAP S/4HANA via APIs without modifying the core
- In-app extensibility: Use controlled, upgrade-safe tools to adapt standard applications
- Integration services: Connect SAP S/4HANA with third-party systems while keeping the core isolated
- Business process automation: Innovate on top of SAP S/4HANA without touching its internals
Think of BTP as your innovation and differentiation layer , not just a place to build apps, but the backbone for driving clean innovation across your landscape.
Where should we start and when?
If you’re planning a move to S/4HANA: Start now. Include clean core principles in your S/4 project charter.
If you’re already on S/4: Begin with visibility using tools like SAP Readiness Check and Custom Code Migration app.
Quick wins: Start with new development requests , enforce clean core principles for all new functionality while you work on retrofitting existing customizations.
Governance foundation:
- Define what clean means for your organization
- Establish approval processes for new development requests
- Create architectural guidelines and review boards
- Set up monitoring to track compliance
How do we measure success?
Establish clear metrics from the start:
Technical metrics:
- Upgrade cycle time (target: quarterly vs. annual)
- System downtime during updates
- Number of customizations requiring rework per upgrade
Business metrics:
- Time-to-market for new business capabilities
- IT maintenance costs as % of IT budget
- Developer productivity (features delivered per sprint)
Ready to Take Action?
Clean core isn’t just about following SAP’s latest guidelines , it’s about positioning your organization for the next decade of digital transformation.
Your next steps depend on where you are:
If you’re still on ECC: Make clean core a cornerstone of your S/4HANA strategy. Don’t replicate yesterday’s problems in tomorrow’s system.
If you’re on S/4 but struggling with upgrades: It’s time for an honest assessment. Every month you delay makes the transition more complex and expensive.
The path forward requires both technical expertise and organizational change management. Most importantly, it requires partners who understand that clean core is not a destination, but a journey.
But here’s the uncomfortable truth: despite good intentions and detailed strategies, most clean core initiatives quietly fail. In our next blog, we explore why that happens and what it reveals about how your SAP landscape is really being managed.
Ready to explore what clean core means for your organization?
Contact us to discuss how we can support your SAP journey.
