SAP has confirmed mainstream maintenance for ECC (EHP 6–8) ends on 31 December 2027, with no further extensions. That date feels distant until you map it against real migration timelines: a full ECC-to-S/4HANA transformation typically runs 18–36 months for a large enterprise. Work backward from December 2027 and the math is blunt — mid-2026 is effectively the last point at which a clean, well-tested migration can still finish on time.
I've now led three of these programs at very different scales: an 8-entity SAP ECC rollout at Subhash Group, a 10-entity S/4HANA implementation at Alhamra Group, and the current enterprise-wide S/4HANA modernization for RAK Government spanning Finance, MM, HR and PS modules. The pattern that separates a smooth go-live from a painful one is never the software — it's data migration discipline, change management, and how early you start talking to the business, not just IT.
A few things I'm telling every CIO who asks me about this deadline right now:
1. Treat “clean core” as a governance decision, not a technical one. Every custom Z-report and workaround you carry into S/4HANA is a future upgrade cost. Decide now what gets left behind.
2. The consultant shortage is real and it's compounding. With roughly 39% of ECC customers having licensed S/4HANA so far, and every remaining customer racing the same deadline, SI and Basis capacity will only get scarcer through 2027. Lock your delivery partner and migration cockpit resources early.
3. Use the forced migration as a modernization multiplier. On the RAK Government program, we're using the S/4HANA move to simultaneously consolidate our data migration cockpit, extend SAP Fiori, and lay groundwork for our Agentic AI platform to query financial and procurement data natively. Don't just lift-and-shift — every deadline-driven migration is also a rare license to fix what's broken.
If your organization hasn't started scoping by now, the conversation with your board needs to happen this quarter, not next.