# S/4HANA MM Simplification and Readiness Checklist > Source: https://netray.co/tools/s4hana-mm-simplification-readiness-checklist > Publisher: Netray (netray.co), AI and integration engineering for ERP and manufacturing systems. > Section: Free Tools ## Short answer Checklist of the S/4HANA changes that affect purchasing and inventory, to review before a conversion or new implementation. ## Category sap ## Erp SAP S/4HANA ## Audience - SAP MM consultant - Project manager - IT manager ## Tool **Kind:** checklist **Groups:** #### Master data **Items:** **Text:** Plan the vendor to business partner conversion (customer vendor integration) **Critical:** true **Text:** Clean duplicate vendors and unused records before conversion **Critical:** true **Text:** Review material number length and external interfaces for the 40 character field **Critical:** true Check that interfaces and EDI maps handle longer material numbers Review material types, plant and storage location data for obsolete entries Check source lists and info records for expired or orphaned data #### Inventory and valuation **Items:** **Text:** Understand that material documents are stored in MATDOC **Critical:** true **Text:** Find custom code that reads MKPF, MSEG or old aggregate tables **Critical:** true **Text:** Plan the material ledger activation, which is required in S/4HANA **Critical:** true Decide on actual costing and the price determination setup Reconcile stock and valuation before the cutover Review stock reports and custom analyses that rely on aggregate tables Check the posting period setup for the new fiscal year variant #### Procurement and invoice verification **Items:** **Text:** Identify which purchasing transactions are replaced by Fiori apps **Critical:** true Review release strategies and workflows for requisitions and orders Check output determination, messages and forms after conversion **Text:** Test the invoice verification flow, including tolerance and blocking **Critical:** true Review GR/IR clearing and open items before cutover Check ariba or external procurement integrations for compatibility #### Planning **Items:** **Text:** Evaluate MRP Live (MD01N) against your current MRP run **Critical:** true Review MRP areas, planning file entries and regeneration needs Check custom MRP exits and user exits for compatibility Confirm planned orders and requisitions are converted correctly Compare sample planning results before and after in a test system #### Custom code and project controls **Items:** **Text:** Run the custom code analysis and review the simplification database **Critical:** true **Text:** Run the SAP Readiness Check or the Simplification Item Check for your release **Critical:** true Identify custom reports and Z-tables that touch MM data **Text:** Plan regression tests for the end to end procure to pay process **Critical:** true Prepare cutover steps for open POs, open invoices and open stock documents Train buyers and warehouse users on the changed screens and apps Define go/no-go criteria and a rollback plan **Scoring Note:** Items marked critical commonly cause project delays or defects when missed. Verify each against the simplification item catalog for your target release. ## Content **Intro:** S/4HANA keeps the familiar MM processes but changes what sits underneath them. This checklist lists the changes in master data, inventory, procurement and planning that tend to cause surprises in a conversion project. **Sections:** #### How to use the checklist **Body:** Use it in the early assessment phase and again before the test cycles. Tick off what is already analysed and assign owners to what is not. The critical items usually involve data model changes, such as business partners and material documents, or custom code that depends on the old structure. Export the result to PDF or Excel for your steering group. #### Where MM changes most **Body:** The biggest structural changes are the business partner as the leading object for vendors, material documents stored in MATDOC and the mandatory material ledger. The material number can be extended to 40 characters, which affects interfaces. MRP Live runs in the database for speed. Several classic transactions are replaced by Fiori apps. SAP publishes the simplification list that describes each change and the required action for your target release. **Bullets:** - Business partner replaces separate vendor maintenance - MATDOC replaces MKPF and MSEG as storage - Material ledger is required - MD01N is the HANA optimized MRP run #### Common mistakes **Body:** Projects often assume MM is a technical upgrade and underestimate data cleansing, especially vendors that block the business partner conversion. Another is leaving custom reports that read legacy tables untested. Teams also forget that interfaces limit the material number length. Finally, plan tests around the full procure to pay flow, because errors often show up only when invoice verification meets the new material ledger. **Cta:** If you are weighing an S/4HANA move and want custom code and data quality assessed using AI over your own system, we can discuss how that works on-prem. **Faq:** #### Is the material ledger really mandatory in S/4HANA? **Answer:** Yes. Material ledger is always active in S/4HANA, though actual costing within it remains optional. Plan for the activation steps and the valuation data migration, and decide on the price determination you want to use. #### What happens to my custom reports that read MSEG? **Answer:** Compatibility views keep many reads working, but performance and results may differ, and writes are not allowed. Run custom code analysis for your release and refactor reports to use MATDOC or released CDS views. #### Do I need to change all vendors to business partners? **Answer:** Yes, S/4HANA uses the business partner as the leading object, and the conversion creates business partners for existing vendors. Clean master data first, since duplicates and inconsistent data slow the conversion. #### Does this checklist replace the SAP simplification list? **Answer:** No. It is a practical prompt list. The official simplification item catalog and tools like the Readiness Check are the authority for your release. Use this list to organize your review and to make sure nothing important is skipped. ## Search terms s4hana mm simplification list, ecc to s4hana mm migration checklist, s4hana business partner vendor conversion, s4hana matdoc impact, s4hana mrp live md01n, s4hana material number 40 characters, s4hana material ledger mandatory, s4hana readiness check mm --- Talk to an engineer: https://netray.co/contact?intent=erp_ai | Machine catalog: https://netray.co/agent/catalog.json