Project plan for an SAP S/4HANA implementation
Moving from SAP ECC to S/4HANA is more than a technical upgrade: custom code has to be cleaned up, processes reviewed, test cycles planned and users trained. This plan shows a brownfield conversion for a manufacturing company with 900 employees and the modules FI/CO, MM, SD and PP.
No sign-up · opens instantly · 52 Weeks · 14 Phases · 121 Tasks · Budget approx. €3,696,000
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SAP ECC to SAP S/4HANA Brownfield Conversion
This project will convert the organization’s existing SAP ECC landscape to SAP S/4HANA using a brownfield approach. It will cover core business processes in FI/CO, MM, SD, and PP, while also addressing custom code, integrations, data quality, and technical readiness. The program must preserve business continuity for a 900-employee manufacturing company and support a controlled go-live at the start of the fiscal year. Strong governance, testing, training, and hypercare are essential to reduce operational and reporting risk.
Phases
Phase 1: Program Mobilization and Governance
Establish the governance model, delivery standards, workstream structure and decision rights for the brownfield conversion. This creates the control framework required to manage the fiscal-year go-live and cross-functional dependencies.
Phase 2: Current-State Assessment and Scope Confirmation
Establish a fact-based baseline of the ECC solution, business processes, plants, interfaces, data objects, reports and custom developments. The phase confirms what will be converted, redesigned, retired or excluded from the S/4HANA scope.
Phase 3: S/4HANA Readiness and Technical Assessment
Determine whether the ECC landscape, custom developments, add-ons, infrastructure, interfaces and security model are ready for conversion. The output is a prioritized remediation backlog with clear technical and business decisions.
Phase 4: Fit-to-Standard and Solution Design
Define the target S/4HANA process design using standard capabilities wherever possible and formally approve only justified deviations. The phase aligns finance, supply chain, sales, manufacturing, reporting, security and plant requirements before build activities begin.
Phase 5: Custom Code Remediation
Remediate custom developments affected by S/4HANA simplification items, changed data models, obsolete transactions and revised integration patterns. Obsolete or low-value developments are retired to reduce conversion risk and future maintenance effort.
Phase 6: Architecture, Integration and Data Migration Design
Finalize the target architecture, integration design, migration objects, ownership model and reconciliation controls. This phase converts the solution blueprint into build-ready technical specifications and measurable data-quality requirements.
Phase 7: S/4HANA Configuration and Development
Configure the S/4HANA core modules and build approved extensions, interfaces, forms, reports, workflows and authorization roles. The phase produces a fully integrated solution suitable for migration rehearsals and formal test cycles.
Phase 8: Data Cleansing and Migration Rehearsals
Improve the quality of master and transactional data and prove the migration approach through repeated trial conversions. Each rehearsal validates transformation logic, load sequencing, reconciliation and the time required for the fiscal-year cutover.
Phase 9: System Integration and End-to-End Testing
Validate the converted solution across modules, plants, external systems and operational volumes. Testing focuses on complete business flows rather than isolated transactions, with formal defect control and regression evidence.
Phase 10: User Acceptance and Business Validation
Enable business key users and process owners to confirm that the solution supports daily operations, controls, reporting and plant-specific requirements. Formal business acceptance is required before final cutover preparation.
Phase 11: Training and Change Readiness
Prepare users and support teams for changed S/4HANA processes, roles and controls. Training is role-based and plant-aware, with key users enabled to support adoption and first-line issue resolution.
Phase 12: Cutover Planning and Go-Live Rehearsal
Convert the implementation into an executable fiscal-year cutover plan with defined timing, ownership, controls, fallback decisions and support coverage. A full rehearsal validates that the production conversion can be completed within the available year-end window.
Phase 13: Final Migration and Fiscal-Year Go-Live
Execute the controlled production conversion at the fiscal-year boundary, load final data and validate financial, operational and technical readiness. Go-live proceeds only after formal business and technology approval.
Phase 14: Hypercare and Stabilization
Stabilize business operations, resolve critical defects and verify performance during the first weeks of live processing. Hypercare ends when operational ownership, support procedures and outstanding issues are formally transferred to business-as-usual teams.
Timeline
Budget
| Item | Qty | Unit price | Total |
|---|---|---|---|
| S/4HANA Conversion Architect | 110 Person days | €1,200 | €132,000 |
| FI/CO Functional Consultant Team | 100 Person days | €1,100 | €110,000 |
| MM and SD Functional Consultant Team | 175 Person days | €1,050 | €183,750 |
| PP and Manufacturing Functional Consultant | 110 Person days | €1,150 | €126,500 |
| SAP Basis and Technical Conversion Lead | 110 Person days | €1,050 | €115,500 |
| ABAP Custom-Code Remediation Team | 460 Person days | €900 | €414,000 |
| S/4HANA Configuration Team | 450 Person days | €1,050 | €472,500 |
| Integration, Workflow, Reports and Forms Specialists | 125 Person days | €1,006 | €125,750 |
| Item | Qty | Unit price | Total |
|---|---|---|---|
| Data Migration Lead and Reconciliation Specialist | 90 Person days | €1,000 | €90,000 |
| Master Data Cleansing Specialists | 240 Person days | €750 | €180,000 |
| Migration Developers and Integration/EDI Specialists | 350 Person days | €975 | €341,250 |
| Test Manager and Quality Assurance Lead | 90 Person days | €950 | €85,500 |
| End-to-End Test Analysts | 140 Person days | €750 | €105,000 |
| Test Data, Automation and Defect Management Tooling | 1 Flat rate | €38,250 | €38,250 |
| Item | Qty | Unit price | Total |
|---|---|---|---|
| Change and Training Lead | 100 Person days | €950 | €95,000 |
| Training Content and Key-User Delivery Team | 1 Flat rate | €215,000 | €215,000 |
| Communications and Adoption Specialist | 60 Person days | €850 | €51,000 |
| Cutover Management, Go-Live Command Center and Plant Travel | 1 Flat rate | €127,000 | €127,000 |
| Extended Functional and Technical Hypercare Support | 100 Person days | €1,000 | €100,000 |
| Item | Qty | Unit price | Total |
|---|---|---|---|
| S/4HANA Conversion Licensing and Subscription Changes | 1 Flat rate | €180,000 | €180,000 |
| Development, Sandbox and Test Environment Hosting | 12 Person days | €15,000 | €180,000 |
| Production Capacity Expansion, Monitoring and Backup Tooling | 1 Flat rate | €60,000 | €60,000 |
| Item | Qty | Unit price | Total |
|---|---|---|---|
| SAP Program Director | 60 Person days | €950 | €57,000 |
| PMO and Project Controls Lead | 70 Person days | €700 | €49,000 |
| Enterprise Architect / Independent QA Reviewer | 62 Person days | €1,000 | €62,000 |
Risks
Fiscal-Year Cutover and Opening-Balance Failure
If the final migration, reconciliation or financial validation is not completed within the approved cutover window in Weeks 46–47, incorrect opening balances, incomplete transactions or unavailable interfaces could prevent the first fiscal period from opening and disrupt statutory, management and cash reporting.
Critical Custom-Code Incompatibility
If ATC findings, simplification items or undocumented custom interfaces remain unresolved after Week 18, obsolete data models, transactions or enhancements may fail during integration testing or production processing.
Master-Data and Migration-Reconciliation Errors
If material, supplier, customer, asset, production or financial master data does not meet approved quality thresholds by the end of Week 26, migration errors may cause incorrect inventory valuation, procurement, receivables, payables, production planning or financial reporting.
Manufacturing Planning and Shop-Floor Disruption
If bills of material, routings, work centers, MRP parameters, production versions or plant-specific settings are incomplete or incorrectly converted by Week 26, MRP, capacity planning, production orders and shop-floor execution may fail after go-live.
Integration, EDI and External-System Failure
If interface mappings and endpoint changes for MES, WMS, EDI partners, banks, tax services, CRM or logistics systems are not validated by Week 35, changed APIs, message formats or certificates may interrupt orders, goods movements, payments, deliveries or statutory submissions.
Insufficient End-to-End and Performance Testing
If testing remains focused on individual modules or excludes peak volumes, month-end closing, MRP runs, warehouse activity and cross-functional exceptions through Week 35, defects may appear only during UAT, cutover or the first fiscal period.
Security, Authorization and Segregation-of-Duties Defects
If converted roles, Fiori access, privileged accounts or segregation-of-duties conflicts are not redesigned and tested before Week 41, users may be unable to perform critical activities or may obtain unauthorized access affecting financial integrity and audit compliance.
Technical Capacity or Conversion-Window Failure
If infrastructure sizing, database capacity, batch scheduling or conversion performance is inadequate by Week 27, high-volume transactions, MRP, closing activities or the fiscal-year conversion may exceed the available processing window.
Scope Growth and ECC-Process Retention
If business units request unapproved ECC customizations or late enhancements after the Week 16 design baseline, solution divergence may increase development effort, consume the reserve and delay testing or fiscal-year readiness.
Specialist-Resource and Vendor-Capacity Constraints
If SAP, ABAP, manufacturing, migration, Basis or testing specialists are unavailable during overlapping Weeks 17–41, configuration, defect resolution and business validation may become bottlenecks and delay the cutover decision.
Inadequate Business Readiness and Training
If role-based training, plant involvement and support preparation are incomplete by Week 41, users may process orders, goods movements, production transactions or financial postings incorrectly and create workarounds after go-live.
Hypercare Overload and Support-Handover Failure
If critical defects, support procedures, monitoring or knowledge transfer remain incomplete at the end of Week 47, the support organization may be unable to resolve incidents during the first close, production cycle or customer billing run.
Stakeholders
Executive Sponsor / Steering Committee
Owns strategic direction, funding, scope escalation, and go-live approval
CIO or Head of IT
Owns technology strategy, risk acceptance, architecture decisions, and internal IT capacity
CFO and Finance Transformation Lead
Approves FI/CO design, financial controls, closing processes, opening balances, and audit readiness
SAP Program Director / Program Manager
Coordinates workstreams, dependencies, milestones, budget, and delivery governance
External SAP Systems Integrator
Provides S/4HANA conversion expertise, configuration, development, migration, and cutover support
SAP Basis and Infrastructure Lead
Owns environments, conversion tooling, performance, transport management, backup, and technical operations
Enterprise Architecture and Integration Lead
Controls interfaces with MES, EDI, warehouse, banking, tax, CRM, and other connected systems
ABAP and Custom Code Lead
Inventories, prioritizes, remediates, and tests custom developments and extensions
Procurement and Materials Management Lead
Validates purchasing, inventory, supplier, valuation, and goods-movement processes
Sales and Distribution Lead
Validates order-to-cash, pricing, delivery, shipping, billing, and customer integration processes
Production Planning and Manufacturing Lead
Validates MRP, BOMs, routings, production orders, capacity planning, and plant execution
Data Migration and Master Data Owner
Defines data quality rules, ownership, migration mapping, and reconciliation for master and transactional data
Test and Quality Manager
Defines test governance, entry/exit criteria, defect management, evidence, and release recommendations
Plant Managers and Business Key Users
Represent site-specific operational needs and approve end-to-end process readiness
Change, Communications and Training Lead
Manages communications, role impacts, training delivery, and adoption activities
Information Security, Internal Controls and Compliance Representatives
Validate access controls, segregation of duties, audit trails, financial controls, and security requirements
Works Council or Employee Representatives, where applicable
Review affected roles, working practices, and employee-impacting changes
Compliance
Comply with GDPR for employee, customer, supplier and contact data migrated or used in test environments, including lawful processing, data minimization, access control, retention, breach handling and masking of non-production data.
Validate FI/CO configuration, opening balances, audit trails, period controls, statutory reports, tax/VAT processing and records retention against applicable local accounting, tax and financial-reporting laws.
Maintain documented internal controls over financial postings, master-data changes, approvals, payment processes, privileged access and segregation of duties, with evidence suitable for internal and external audit.
Apply the organization’s information-security policy and relevant ISO 27001-aligned controls, including secure configuration, vulnerability management, encryption, logging, backup/restore, incident response and access recertification.
Confirm SAP licensing, S/4HANA subscription or maintenance rights, third-party add-on compatibility, interface-provider contracts and EDI partner obligations before production conversion.
Maintain documented backup, disaster-recovery, rollback and business-continuity procedures, and demonstrate recovery and fallback capability before the fiscal-year go-live.
Complete formal change-impact consultation with the Works Council or employee representatives where required, covering affected roles, working practices, monitoring and training implications.
Milestones
- Week 3
Approved program charter, governance structure, RACI matrix, integrated delivery plan and confirmed core project team
Depends on: Program mobilization and governance - Week 8
Approved ECC baseline, application and interface inventory, data-object inventory and signed conversion scope
Depends on: Current-state assessment and scope confirmation - Week 10
Approved S/4HANA readiness report, prioritized remediation backlog and technical conversion prerequisites
Depends on: S/4HANA readiness and technical assessment - Week 16
Signed S/4HANA solution blueprint with approved process design, deviations, reporting model, roles and integration principles
Depends on: Fit-to-standard and solution design - Week 18
Approved custom-code remediation backlog with completed priority fixes, retired objects, ATC clearance and unit-test evidence
Depends on: Custom code remediation - Week 19
Approved technical architecture, interface specifications, migration design, data ownership model and reconciliation framework
Depends on: Architecture, integration and data migration design - Week 26
Completed migration rehearsal with reconciled results, approved data-quality thresholds and signed migration-object ownership
Depends on: Data cleansing and migration rehearsals - Week 27
Configured S/4HANA solution with approved developments, interfaces, reports, workflows, roles and completed module unit-test preparation
Depends on: S/4HANA configuration and development - Week 35
Completed integration and end-to-end test cycle with agreed defect thresholds, performance evidence and approval to enter UAT
Depends on: System integration and end-to-end testing - Week 41
Signed UAT acceptance by FI/CO, MM, SD, PP and plant process owners with approved defect disposition
Depends on: User acceptance and business validation - Week 41
Approved training curriculum, trained key-user network, published communications and documented business-readiness assessment
Depends on: Training and change readiness - Week 45
Approved cutover runbook and successful timed go-live rehearsal meeting conversion, validation and fallback criteria
Depends on: Cutover planning and go-live rehearsal - Week 47
S/4HANA live at the start of the fiscal year with reconciled opening balances, active interfaces and formal go-live approval
Depends on: Final migration and fiscal-year go-live - Week 52
Stable first-period operations, completed financial reconciliation, accepted performance levels and formal transition to business-as-usual support
Depends on: Hypercare and stabilization
How this plan was created
This plan was created by PathHub AI from a single description: “Move from SAP ECC to SAP S/4HANA (brownfield conversion) in a manufacturing company with 900 employees, modules FI/CO, MM, SD and PP, including clean-up of custom code, test cycles, training and hypercare. Go-live at the start of the fiscal year.” — without company context. With your departments, approval processes and compliance requirements it becomes much more precise.
Related documents
The requirements specification usually comes before the project plan — here is the matching example with Word download.
Obligations with lead time: what many think of too late
These obligations are typically triggered by an SAP S/4HANA implementation (example: Germany). PathHub AI schedules them with lead time, warns when the schedule is too tight and shows the rule with its criteria under “Rule & evidence”, which you tick off and back with evidence. Not legal advice.
Rule & evidence
Why: The new system processes personal data of customers or employees.
- Legal basis for every processing of personal data (consent, contract, legal obligation, legitimate interest)
- Complete record of processing activities (Art. 30) for all processes
- Data Processing Agreements (DPA) with all sub-processors
- Data Protection Impact Assessment (DPIA) for high-risk processing
- Technical and organisational measures (TOM) documented
If breached: Fines up to €20 million or 4% of global annual revenue — whichever is higher. Plus civil damages claims by affected individuals.
Rule & evidence
Why: The provider processes personal data on your behalf (cloud, maintenance, support).
Legal basis: GDPR Art. 28: the contract must be in place before processing starts, including tests with real data or data migration.
- Data Processing Agreement (DPA) with cloud provider
- SLA with availability, RPO, RTO
- Exit and portability clause
- Data localisation and transfer mechanism (SCC / adequacy)
If breached: Civil claims for data loss; recourse depends on contract. GDPR fines for non-compliance.
Rule & evidence
Why: Almost any software logs user actions and is therefore suitable for monitoring performance or behaviour.
Applies: only if a works council exists
Legal basis: Sec. 87(1) No. 6 Works Constitution Act: co-determination for technical systems suitable for monitoring behaviour or performance; suitability is enough. Without agreement the system must not be introduced.
- Enable works council election from 5 eligible employees upward
- Co-determination on working time, monitoring systems, IT rollouts (§87)
- Hearing before every dismissal (§102) — written with reasons
- Balance-of-interests and social plan on operational changes (§111)
If breached: Dismissals without works council hearing are void. Administrative fines up to €10,000 per violation. Criminal liability (§119) for obstructing the works council up to 1 year imprisonment.
Rule & evidence
Why: Tax-relevant data must be retained completely, unalterably and auditably, also after the system change.
Applies: if the system processes accounting or tax-relevant data (ERP, invoices, POS)
- Process documentation for all tax-relevant systems and procedures
- Complete and unalterable records, changes are logged
- Retention of tax-relevant documents for the statutory period (generally 8 or 10 years)
- Data access for tax audits possible (Sec. 147(6) German Fiscal Code)
- Receipt of structured e-invoices (XRechnung, ZUGFeRD) since 1 Jan 2025
- Issuing e-invoices to domestic businesses: from 2027 for prior-year turnover above EUR 800,000, from 2028 generally for all (exceptions incl. small-amount invoices, small businesses)
If breached: Formal defects can lead to the bookkeeping being rejected and the tax base being estimated (Sec. 162 German Fiscal Code); refusing data access can trigger a delay penalty (Sec. 146(2c)).
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