To secure the long-term viability of its SAP HCM system, Stadtwerke München decided to upgrade to SAP S/4HANA. The challenge was that their existing HCM system was highly complex and included numerous custom developments. SWM had largely managed the compatibility of these customizations in-house. However, SAP S/4HANA introduces new concepts that require adjustments to the existing system environment – such as the implementation of the SAP Employee Business Partner model and the adaptation of custom code to the HANA database. FI-related changes also required updates to the payroll and payment processes in the HCM system.
When the migration project was launched in December 2023, the focus was on a comprehensive system and data assessment. Using the SAP Readiness Check, Simplification Items, and the ABAP Test Cockpit (ATC), the project team gained full transparency into the existing HCM system, including its data structures and processes. Based on these insights, detailed conversion and cutover concepts were developed in joint workshops.
The migration itself was executed in four phases. First, a system copy was created and the HCM landscape was technically converted to S/4HANA. Next, SAP HCM for S/4HANA was activated and tailored to the organization’s specific requirements, including interface adjustments, Fiori Launchpad implementation, and house bank configuration. In the third phase, the Employee Business Partner was set up and further required adaptations were completed. Finally, extensive testing was carried out before the new system went live.
A seamless, on-time transition
The project was successfully completed on schedule by the end of August 2024. Within just nine months, the full system transition was accomplished – preserving all existing functionality while introducing new S/4HANA-specific components.
Close collaboration between SWM and Natuvion was a key success factor, supported by transparent communication via Jira, regular project meetings, and fast alignment through Microsoft Teams. Targeted knowledge transfer also enabled SWM to independently take ownership of many tasks throughout the migration process.
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