S/4HANA conversion planning sets the route from ECC to S/4HANA across brownfield, greenfield, RISE, PCE and BTPEA. The Admodum read on the 2027 mainstream maintenance horizon, the route decision tree, the conversion-credit mechanic and the renewal posture.
SAP mainstream maintenance for ECC 6.0 and the wider Business Suite 7 closes at the end of 2027. After mainstream maintenance close, SAP Extended Maintenance is available through 2030 at an additional maintenance fee (typically a two-percentage-point uplift to the standard maintenance rate). After 2030, the SAP Customer-Specific Maintenance regime applies (which carries a higher cost and does not include legal-change or regulatory-update content).
The 2027 horizon is the practical horizon for most SAP-customer planning. The principal conversion-decision deadline (for a buyer who wishes to be on S/4HANA at mainstream maintenance close) is typically eighteen to twenty-four months before the close date, which sits in the mid-2026 to early-2026 window. The wider ECC end of mainstream spoke reads the horizon in commercial detail.
The brownfield route is the in-place conversion of the existing ECC estate into S/4HANA. The buyer's existing custom code, configuration, master data, transactional history and integration footprint move with the conversion (subject to the Simplification List remediation). The named-user category set is rebuilt to the S/4HANA categories (Advanced, Core, Functional, Self-Service); the conversion-credit mechanic does not apply on the brownfield-stay-on-premise route (the existing licences apply directly to S/4HANA on-premise).
The brownfield route reads commercially for estates with substantial custom code, deep configuration and integration depth where the cost-of-rebuild on a greenfield re-implementation is prohibitive. The wider SAP clean core spoke reads the principle that constrains brownfield custom-code retention.
The greenfield route is the new S/4HANA implementation onto a clean install. The buyer redesigns the process model, the configuration, the master data, the custom-code footprint, the integration footprint. Historical data is migrated selectively, not lifted-and-shifted. The greenfield route reads commercially for estates with material technical-debt, outdated process design or fragmented configuration where the cost of the rebuild is paid against the cost of the carried-forward debt.
The greenfield destination is typically RISE, PCE or the on-premise plus BYO-hyperscaler construct (not the brownfield-stay-on-premise). The conversion-credit mechanic applies on the cloud destinations. The wider RISE bundle anatomy spoke reads the RISE destination.
The Simplification List is the SAP-published list of ECC functionality that is replaced, retired or substantively changed in S/4HANA. The List is structured by application area and by Simplification Item: each Item documents the change, the replacement functionality (where one exists), the technical-remediation requirement and the timing horizon. The Simplification List drives the custom-code remediation scope: every custom code object that touches a Simplification Item must be remediated as part of the conversion.
The remediation scope drives the technical timeline; the technical timeline drives the licensing-decision timeline. The principal anti-pattern is the licensing decision taken before the Simplification List assessment is complete, with the technical reality emerging mid-implementation as a re-licensing event. The wider SAP developer licences spoke reads the developer-side licence consequence.
The conversion-credit mechanic applies the existing on-premise licence value as a credit against the destination subscription (RISE, PCE, GROW or another cloud variant). The SAP-side policy values the on-premise estate at a defined recovery rate (a percentage of the original licence value); the recovery rate is a negotiable variable, not a fixed parameter.
The buyer-side artefact is the on-premise valuation schedule (every licence, every original price, every maintenance attachment, every shelfware position, every named-user recategorisation impact). The wider SAP cloud conversion credits spoke reads the conversion-credit mechanic in negotiation detail.
The renewal posture is the commercial window question. A buyer with a maintenance renewal that falls before the conversion decision typically extends the renewal by one or two years (preserving the option), not by five (which closes the option). The renewal extension carries the BATNA reading into the conversion negotiation: the buyer who does not need to commit to a specific destination at renewal carries a stronger position into the conversion negotiation.
The wider engagement sits in the SAP practice; the aggregated reading list sits in the SAP knowledge hub; active renewal moments route to the Renewal Programme; active audit moments route to Audit Defence.
The bundled subscription that is one of the principal conversion destinations.
The conversion-credit mechanic that values the existing on-premise estate against the cloud destinations.
A senior Admodum SAP advisor will read your ECC estate, your Simplification List exposure and your renewal-cycle position against the five conversion routes on a private call. The decision is one event; the planning runs ahead.