SAP legacy system decommissioning: Why it matters more than ever in 2026

Author: Priyasha Purkayastha, Global Content Manager, TJC Group

SAP legacy system decommissioning has become one of the most pressing priorities for enterprises worldwide. In 2026, the window for action is narrowing, and the cost of inaction is growing. This article explores why decommissioning legacy systems is no longer optional and how organisations can approach it strategically. Read on to learn more!

Introduction

The enterprise technology landscape is undergoing a fundamental transformation. As SAP phases out mainstream maintenance for SAP ECC by the end of 2027, organisations that have not yet begun their transition to SAP S/4HANA face mounting pressure. In 2026, the urgency is at its peak, as typical S/4HANA migrations require 12 to 18 months of implementation, not including planning and training phases.

Yet migration is only part of the equation. What happens to the old systems once the new landscape is live? This is where SAP legacy system decommissioning enters the picture. It is the process of safely retiring outdated SAP and non-SAP systems while preserving essential historical data in a compliant, accessible format.

Organisations that delay decommissioning risk accumulating unnecessary costs, exposing sensitive data to cybersecurity threats, and falling behind on regulatory compliance. This article provides a comprehensive overview of why decommissioning legacy systems should be a top strategic priority in 2026 and how to approach it effectively.

What is SAP legacy system decommissioning?

SAP legacy system decommissioning is the structured process of retiring an SAP or non-SAP system that is no longer needed for day-to-day business operations. Unlike a simple system shutdown, decommissioning involves careful planning to ensure that valuable historical data is extracted, archived, and made accessible before the system is permanently switched off.

The process typically includes a thorough assessment of the data landscape, extraction of relevant data and documents, migration into a secure and compliant repository, and the eventual shutdown of the legacy environment. It is a more complex undertaking than data archiving alone, as it involves the retirement of an entire system rather than a subset of data.

For a deeper understanding of the terminology involved, our guide to SAP data management key terminologies offers a helpful starting point.

Why 2026 is a critical year for SAP decommissioning

The year 2026 represents a pivotal moment for organisations still running SAP ECC. With mainstream maintenance ending in 2027, and organisations on Enhancement Package 5 (EHP5) having already lost mainstream support at the end of 2025, the clock is ticking. Starting a migration in 2026 without a decommissioning strategy is a significant risk.

Competition for SAP talent and consulting resources is intensifying as more organisations rush to complete their transitions. Those that begin late face increased project risks, higher costs, and the possibility of extended periods without full support coverage. The path to S/4HANA requires organisations to think carefully about what happens to their legacy systems.

Furthermore, SAP is focusing all new features and innovations exclusively on S/4HANA. Remaining on ECC means missing out on capabilities that competitors are already leveraging, from embedded analytics to AI-driven process automation. In 2026, the question is no longer whether to decommission but how quickly it can be done.

Key benefits of decommissioning legacy systems

Understanding the decommissioning legacy system benefits helps build a compelling business case for action. Here are the most significant advantages:

Substantial cost reductions

One of the most immediate and tangible benefits is cost savings. Legacy systems are expensive to maintain, requiring specialised hardware, software licences, infrastructure, and personnel. Complete decommissioning of old systems can lead to savings of 60 to 80 per cent in operating costs. A documented case from TJC Group shows a global manufacturing company saved over $250,000 annually by decommissioning its legacy SAP ECC system.

Simplified IT landscape

Retiring obsolete systems reduces the complexity of your IT environment. Fewer systems mean fewer integration points, less monitoring overhead, and a more streamlined infrastructure. This simplification frees up IT resources to focus on innovation and strategic initiatives rather than maintaining outdated technology.

Improved data quality

The decommissioning process provides an opportunity to cleanse and rationalise data. On average, only about 20% of existing data needs to be transferred to S/4HANA. By carefully evaluating what to retain and what to archive, organisations can enter their new landscape with higher quality data, which is essential for AI-driven analytics and reporting in S/4HANA.

Faster migration timelines

Reducing the volume of data that needs to be migrated directly shortens project timelines. Typical data volume reductions of 30 to 70 per cent translate into faster conversion and verification times, minimising system downtime and reducing overall project costs.

The hidden costs of keeping legacy systems alive

Many organisations underestimate the true cost of keeping legacy systems operational. Beyond the obvious expenses of hardware and licences, there are several hidden costs that accumulate over time.

Firstly, finding experts who understand how to manage ageing legacy software is increasingly difficult and expensive. The older a system becomes, the harder it is to source the knowledge required to operate and maintain it. This creates a dependency on a shrinking talent pool, driving up personnel costs.

Secondly, legacy systems require ongoing monitoring of servers, runtime environments, and operating systems. Data growth continues year on year, demanding additional storage capacity and management effort. These incremental costs may seem small individually but compound significantly over time.

According to several research and reports, up to 71% of an organisation’s IT budget can be consumed by maintaining outdated legacy systems. This is budget that could be redirected towards digital transformation, innovation, and competitive advantage. For a detailed breakdown, read our article on the hidden costs of legacy systems.

Cybersecurity risks of legacy SAP systems

Legacy systems represent one of the most significant cybersecurity vulnerabilities in the enterprise landscape. Additionally, keeping up with patches and system updates remains a major challenge for IT professionals managing SAP systems. The list of SAP vulnerabilities requiring close monitoring continues to grow.

When SAP ends maintenance for ECC, security patches will no longer be provided, leaving these systems exposed to evolving threats. Unpatched systems are prime targets for cyberattacks, and the consequences of a breach can be devastating, ranging from data theft to operational disruption and regulatory penalties.

Legacy data that is not encrypted or protected by adequate access controls poses a particularly high risk. Obsolete systems, especially neglected virtual machines, are frequently targeted by attackers precisely because they are unattended. Decommissioning legacy systems for better cybersecurity is not just a best practice; it is a strategic imperative.

Compliance and regulatory drivers for decommissioning

Regulatory compliance adds another layer of urgency to SAP legacy system decommissioning. Legal regulations and data privacy requirements such as the GDPR, CCPA, and other regional frameworks cannot be frequently enforced on obsolete systems. These systems were often designed long before modern data protection regulations were introduced.

Non-compliance can result in heavy financial penalties and significant reputational damage. Control authorities have been known to specifically target archive systems and legacy environments during audits. Organisations are legally required to retain historical data for tax, audit, and regulatory purposes, often for periods of seven to ten years or more.

SAP legacy system decommissioning provides the safest path forward. By extracting data into a compliant repository, organisations ensure that historical records remain accessible for audits and regulatory enquiries while eliminating the risks associated with maintaining outdated systems. For SAP users concerned about GDPR compliance, decommissioning combined with proper data governance is essential.

A phased approach to SAP legacy system decommissioning

A successful decommissioning project follows a structured, phased approach. Rushing the process or treating it as an afterthought can lead to data loss, compliance gaps, and unexpected costs. Here is a recommended roadmap based on best practices for navigating legacy system decommissioning:

Phase 1: Assessment and retention definition

The first step involves a comprehensive inventory of all legacy applications, data, and integrations. Organisations must define a data retention strategy aligned with legal and regulatory requirements. This phase identifies which data must be preserved, which can be archived, and which can be safely deleted.

Phase 2: Data extraction and validation

During this phase, relevant data, documents, attachments, and reports are extracted from the legacy system. At TJC Group, we favour a 100% extraction of accessible non-empty table data to avoid missing any relevant information. Business users should be consulted to anticipate their requirements and limit unexpected custom requests later.

Phase 3: Migration to a compliant repository

Extracted data is migrated into a secure, compliant repository that supports ongoing access for reporting, audits, and regulatory enquiries. This repository must maintain the business context of the data, ensuring historical records remain meaningful and legally defensible.

Phase 4: System shutdown and disposal

Once all data has been verified and stakeholders have confirmed accessibility, the legacy system can be permanently shut down. This includes decommissioning associated infrastructure, terminating licences, and securely disposing of hardware.

For organisations on the journey from sunsetting to decommissioning, understanding these phases is critical to a smooth transition.

Tools and solutions for SAP decommissioning

Several tools and solutions support the SAP decommissioning process. SAP’s own Information Lifecycle Management (ILM) solution provides tools and techniques for archiving data from legacy systems into SAP archive files. These files offer two key benefits: reduced data size through compression and read-only status that fulfils audit requirements.

For a more comprehensive approach, TJC Group’s ELSA (Enterprise Legacy System Application) is an SAP-certified solution designed specifically for decommissioning challenges. ELSA makes accessing data from retired SAP and non-SAP legacy systems as simple as possible. It can be deployed on-premises, through SAP Business Technology Platform, or as a SaaS solution.

ELSA supports both SAP and non-SAP decommissioning, eliminating the complications of managing data across multiple sources. Its architecture balances advanced capabilities with practical, real-world application, making it suitable for organisations of all sizes. Combined with options like RISE with SAP, organisations have flexible pathways to modernise their entire landscape.

Sustainability and the environmental case for decommissioning

Beyond cost and compliance, SAP legacy system decommissioning contributes to environmental sustainability. Data centres have become one of the largest consumers of electricity globally, and the volume of data being stored continues to rise, driving power consumption ever higher.

Old on-premises legacy systems consume significant energy and require physical space. By retiring these obsolete systems, organisations reduce their carbon footprint and support corporate sustainability initiatives. This is an easy win at a time when businesses everywhere are under pressure to demonstrate environmental responsibility.

Additionally, newer in-memory HANA systems, while more efficient in processing, also require substantial electricity to run. Downsizing the overall system landscape through decommissioning helps offset this demand. For organisations with ESG (Environmental, Social, and Governance) reporting obligations, decommissioning provides measurable improvements in energy efficiency.

Key takeaways

SAP legacy system decommissioning is a strategic necessity in 2026, not merely a technical housekeeping exercise. Here are the essential points to remember:

Act now, not later: With SAP ECC mainstream maintenance ending in 2027, 2026 is the last practical year to begin a well-planned decommissioning initiative alongside your S/4HANA migration.

Quantify the cost benefits of decommissioning: Legacy systems can consume up to 71% of IT budgets. Decommissioning can reduce operating costs by 60 to 80 per cent, freeing resources for innovation.

Prioritise cybersecurity: Unpatched legacy systems are a growing security liability. Decommissioning eliminates this attack surface entirely.

Ensure regulatory compliance: Extract historical data into a compliant repository to meet tax, audit, and data privacy obligations without the burden of maintaining obsolete systems.

Leverage proven solutions: Tools like TJC Group’s ELSA and SAP ILM provide structured, certified approaches to decommissioning that preserve data integrity and accessibility.

TJC Group, with over 25 years of expertise in SAP data management and legacy system decommissioning, partners with organisations worldwide to navigate this critical transition. Whether you are planning your S/4HANA migration or looking to retire systems that are no longer delivering value, our team can help you build a strategy that reduces costs, ensures compliance, and protects your data. Contact us today to learn more.

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