OstrellThe 2027 deadline: a realistic S/4HANA timeline, working back from go-live
SAP ECC mainstream maintenance ends at the end of 2027. Here's how long each phase of an S/4HANA move really takes, and when you need to start.
Ostrell Consulting ·
SAP ECC 6.0 mainstream maintenance ends at the end of 2027. Optional extended maintenance is available to the end of 2030, at extra cost. Those dates are fixed. The question is how much room you leave yourself.
Work back from go-live
The simplest way to plan is to pick a target go-live and work backwards. For a typical mid-sized organisation, the phases look something like this. Your numbers will differ, which is exactly why an assessment comes first.
| Phase | What happens | Typical duration |
|---|---|---|
| Readiness assessment | Custom code, data, integrations, route and business case | [4 to 8 weeks] |
| Partner and contract decisions | Route, licences, RISE with SAP or not, delivery partner | [1 to 3 months] |
| Prepare and explore | Detailed design, fit-to-standard workshops | [2 to 4 months] |
| Realise | Build, data migration cycles, integration | [4 to 8 months] |
| Test and cutover rehearsals | System, integration, user acceptance, performance, dress rehearsals | [2 to 4 months] |
| Deploy and hypercare | Go-live, stabilisation | [1 to 3 months] |
Add those up and it’s easy to see why organisations that start late end up rushing, paying for extended maintenance, or both.
What slows programmes down
- Custom code nobody understands. Thousands of objects, many unused. Sorting keep, rework and retire early saves months later.
- Data quality. Duplicate business partners, open items that never closed, missing master data. Data problems surface late unless you look early.
- Decisions without facts. Route debates that run for months because nobody has looked inside the system.
- Too few senior people. Design decisions made by the least experienced people on the project.
What helps
- A readiness assessment that uses your real system data, not a questionnaire.
- AI-assisted code and usage analysis to shorten the assessment.
- Cutover rehearsals planned from the start, not squeezed in at the end.
- One page of honest status every week.
Our view
The deadline is fixed. The panic is optional. If you haven’t started, begin with the facts. Get an S/4HANA readiness check.
