The dates first, because everything else follows from them. For SAP ERP 6.0 on enhancement packages 0 through 5, mainstream maintenance has already ended — those systems moved to customer-specific maintenance in late 2025. For enhancement packages 6, 7 and 8, mainstream maintenance runs until 31 December 2027. After that, optional extended maintenance is available until 31 December 2030 — at a premium of roughly 2% on top of the existing maintenance base, and only for systems on EhP 6 or above.
Now the statistic. Independent research on the S/4HANA transition suggests that only around 57% of ECC customers will have completed their move when mainstream maintenance ends in 2027. Read that from the other side: nearly half the installed base will be mid-flight or not yet started, all drawing on the same limited pool of experienced consultants, at the same time.
That is the real deadline risk for a mid-size business — not that SAP switches your system off (it does not), but that the market around you tightens. Partner capacity gets scarcer and pricier as 2027 approaches; the best consultants get locked into multi-year enterprise programmes; and a rushed migration is precisely the kind of project that fails expensively.
What we recommend, and it is deliberately boring: get a readiness assessment done now, even if you intend to move late. It costs weeks, fixes nothing prematurely, and converts an unknown deadline into a plannable programme — with your route (greenfield, brownfield or selective) chosen on evidence while every option is still open.
Sources: SAP maintenance strategy; SEIDOR — Understanding SAP ECC deadlines; Basis Technologies — The True State of S/4HANA.