Do This Homework Before You Sign an S/4HANA SOW

The least expensive weeks of an ECC to S/4HANA migration are the ones before any partner is under contract. Much of what an implementation team will ask for in its first month, your own people can produce in advance, using tools SAP already provides to customers on maintenance. 

Done well, this homework shortens scoping, sharpens partner proposals and gives the CFO a business case built on your data rather than industry averages. With ECC mainstream maintenance ending in December 2027, those weeks are worth more than they used to be. 

Step one: let your own data build the business case

SAP Signavio Process Insights, discovery edition, analyzes data extracted from your ECC system and shows how your core processes actually perform across finance, procurement, order-to-cash and supply chain. SAP offers it at no charge to customers under an SAP maintenance agreement, and each report now arrives with an executive summary. 

What comes back is more useful than a generic ROI deck. You get process flows with the blockers marked, performance indicators by line of business, recommendations tied to automation and S/4HANA capabilities, and an estimate of the monetary value of fixing what it finds. Purchase orders raised after the invoice arrives, manual price overrides on sales orders, late goods receipts: these are patterns a CFO recognizes immediately, and they turn a technology request into an operating case. 

Step two: measure how ready the system is

SAP Readiness Check reads your ECC system and reports what a conversion will touch. That includes the simplification items relevant to you, the add-ons and business functions that need attention, the custom code affected by data model changes, and sizing for the target system. SAP Note 2913617 explains how to run it for an S/4HANA conversion. 

Pair it with usage data. Readiness Check tells you which custom objects will break; usage logging tells you which of them anyone still runs. The overlap between those two lists is usually far shorter than the first list alone, and that overlap is your real remediation scope. 

Step three: choose the transition path on purpose

There are three ways to leave ECC, and the choice drives cost, timeline and how much history you keep. 

A system conversion, the brownfield route, converts your existing ECC system to S/4HANA Cloud, private edition, carrying configuration, custom code and history with it, and can be combined with a change of hosting provider. A new implementation, the greenfield route, builds a fresh system on SAP’s current best practices and brings over master data and open items, with a single cutover or a rollout plant by plant. Selective data transition sits between the two: you keep the configuration and data you choose, by company code, time slice or process, and redesign the rest. It depends on specialist tooling and experience, so only a small number of partners deliver it well. 

Customers already running S/4HANA on premises have a simpler move, a straight transfer into the private cloud edition at the same release. 

Whichever route you pick, the commercial model changes as well. RISE with SAP replaces perpetual licenses plus annual maintenance with a subscription, so finance should see that shift modeled early rather than discovering it at contract stage. 

Step four: decide which data deserves the trip

Data is where good migrations quietly go over budget. Moving every historical record into S/4HANA inflates storage, lengthens the cutover and imports years of duplicates. A better rule: migrate what the business needs to operate and to meet audit and retention obligations, and archive the rest somewhere it can still be reached. 

S/4HANA also forces some cleanup you cannot skip. Customers and vendors, held separately in ECC tables KNA1 and LFA1, merge into a single Business Partner object, and every conflict between those records has to be resolved before conversion. Credit management moves to the FSCM-based model. MRP Live changes how planners run and read MRP. Each of these is a simplification item with real user impact, and each needs its own test and training plan. 

Start the Business Partner cleanup now. It is the longest-lead data task in most conversions, and none of it requires a partner. 

Plan for the people side early

Technical readiness gets most of the attention. User readiness decides whether go-live week is calm. Planners, buyers and accountants will meet new SAP Fiori screens and changed logic in transactions they have used for fifteen years. Budget for more than one round of training, and run user acceptance testing on real scenarios pulled from your plants rather than scripts the project team wrote. 

Where to start on Monday

For the CIO: request the Signavio discovery analysis and run Readiness Check alongside usage logging this month. Together they give you a factual picture of scope before the first proposal lands on your desk. 

For the CFO: take the Signavio value estimate and the transition path options into the next budget review, and ask for each path to be priced with the subscription shift included. 

Once those outputs are in hand, KloudData can review them with your team and pressure-test the path, including whether a selective data transition fits better than a full conversion. Whoever you hire, make sure they start from your evidence and adapt their template to it. 

Homework done early is the cheapest risk reduction in the entire program.