Custom Code and Technical Debt: What Actually Drives S/4HANA Migration Cost

Custom Code and Technical Debt: What Actually Drives S/4HANA Migration Cost

Custom ABAP code and the technical debt built up around it are usually the biggest wildcard in an S/4HANA cost and timeline estimate. With SAP's December 2027 deadline fixed, getting an honest read on that code early is what separates a real budget from a guess, and AI-assisted analysis can help get there faster.

SAP's mainstream maintenance for ECC ends December 31, 2027. That date alone would be reason enough to plan a migration, but the pressure doesn't stop there. As the installed base shifts toward S/4HANA, the pool of consultants, systems integrators, and third-party tools built around ECC-era SAP thins out too. Waiting doesn't just risk running an unsupported system. It risks doing so with fewer people left who know how to support it.

For most organizations, though, the deadline isn't the hard part of the decision. The hard part is what's sitting inside their own systems: custom ABAP code accumulated over ten, fifteen, twenty years, much of it undocumented, built by developers who've since moved on. Before anyone can price out a migration or commit to a timeline, someone has to figure out what that code actually does, what's still load-bearing, and what can be safely left behind. Get that assessment wrong, or start it too late, and it becomes the thing that blows up both the budget and the schedule. AI-assisted tools are increasingly part of how teams get through that assessment faster, but the underlying work, and the risk of getting it wrong, is the real subject here.

smartShift's analysis of typical SAP ECC environments puts the average system at roughly 22,000 custom objects and 2.7 million lines of executable custom code, carrying an estimated 300,000 individual technical-debt issues spanning performance, security, and stability concerns. None of that means custom code itself was a mistake. smartShift's own research found that 95% of organizations run