Modernizing Legacy Systems: Why Now

Modernizing legacy systems is no longer a topic for the future but one of the most pressing tasks for mid-sized companies that want to remain competitive. We see daily how strongly the demands on IT infrastructures have changed: cloud services, mobile applications, and an ever-growing volume of data place enormous demands on outdated systems. But for many firms, the question is whether the investment in IT modernization pays off. From our perspective, a precise look at return on investment is indispensable here in order to realistically assess potential risks.

With the term "IT modernization ROI," we address a central metric that guides management and budget officers in their decisions. Anyone who fails to calculate the ROI thoroughly exposes themselves to the danger of misinvestments and expensive project cancellations. According to investigations, many companies do not have a clear overview of their IT project costs, which can lead to either too cautious planning or large amounts being invested in solutions whose added value cannot be assured [1].

Our goal in this article is to show the most important steps for calculating the ROI when replacing legacy systems. We consider not only the direct cost factors — license and implementation costs — but also hidden items such as ongoing maintenance, technical debt, or training expenses. This complete inventory helps you to capture all the economic effects of the modernization in order to present the business case to management with sound footing.

In our consulting practice, mid-sized businesses prove particularly agile when they phase out legacy systems gradually instead of renewing everything in one go. Various pilot projects, meticulous controlling, and meaningful KPI reports are important instruments for measuring progress and success at every modernization step. We also recommend taking compliance requirements such as data protection violations or audit obligations into account early. You will find further background, for example, in our article on GDPR and legacy systems.

Modernizing legacy systems is never just a technical matter but always also a question of organization and culture in companies. Indeed, involving employees plays a leading role. According to studies, the ROI of digitalization projects rises by up to 40 to 60 percent when this transformation is designed in a way that fosters team spirit and willingness to learn [2]. It thus becomes clear: the question of whether modernization is worthwhile has more dimensions than pure IT costs.

Understanding the ROI

To make a targeted decision, we first have to clearly define what return on investment actually means. In short, ROI is usually calculated using the formula: ROI = (Net gain from the investment – investment costs) / investment costs Both material gain (such as revenue increases and cost reductions) and intangible benefit (such as improved employee satisfaction or image-enhancing effects) are considered [3].

In the context of legacy system modernization, uncertainties often arise because projects of this magnitude have long-term effects. This means that the effects sometimes become visible only after months or even years. For example, migration to a cloud infrastructure can cause short-term costs but bring scaling advantages over the long run. Such considerations must flow into the ROI calculation so that we can realistically estimate beforehand after what period the modernization will pay off.

Qualitative factors also play an important role. According to a study by RolandZimmermann.de at the time, factors such as customer satisfaction or rising employee motivation can only be valued in monetary terms to a limited extent but nevertheless influence the overall picture of profitability. For example, an innovation culture created by IT modernization can establish new business models or strengthen partnerships. The point here is to create a comprehensive calculation model that takes all relevant components into account, from pure cost savings to brand value increases.

A frequent stumbling block in using ROI metrics is neglecting hidden items. These include maintenance costs, longer-term software updates, IT security, or expenditures for employee training. Especially in older infrastructures, such factors add up. A systematic approach is therefore important, in which we list every cost type and every benefit factor — including any opportunity costs.

To make all of this more tangible, it is worth formulating a clear definition of project boundaries. Where does the modernization project begin and where does it end? Are only parts of the existing infrastructure being replaced, for example, or is a complete replacement planned? Based on this, we can then discuss the full cost structure and make the ROI as precise as possible.

Properly Evaluating Project Costs

The investment costs for a legacy system modernization comprise considerably more than mere license fees. In many cases, the lion's share consists of planning, conception, implementation, and long-term maintenance. Some firms underestimate these aspects, leading to negative budget surprises. Costs for additional personnel or temporary production interruptions are often not adequately accounted for, which can distort the ROI.

It must also be borne in mind that existing legacy systems often have extensive batch processing chains and complex interfaces to third-party applications. A switch is thus usually not trivial and causes migration as well as integration costs. Hidden costs tend to occur when we discover during the project that individual modules of our legacy solution are tightly intertwined with other applications. This shows how sensible it is to work with pilot phases and feasibility analyses before completely separating from an old system.

Ongoing operating costs must also be realistically captured, especially when we rely on cloud models. In practice, we often experience that newly introduced systems do bring low costs for server maintenance but, on the other hand, contractual expenses for software subscriptions or additional security features arise. Or we have to bring in external service providers to a certain extent to maintain security-relevant software. According to a study by Software Logic, taking such hidden and ongoing costs into account is essential to obtain an undistorted assessment of the ROI [1].

In addition, we should ask ourselves whether the modernization is carried out under a Time-and-Materials (T&M) model or at a fixed price. Depending on the project scope, different billing models prove sensible. The T&M model offers flexibility when requirements are unclear, while fixed-price approaches offer planning security. Start-ups developing MVPs often resort to T&M because they have to react quickly to changes [4]. In larger mid-market projects, a hybrid model consisting of a fixed-price element plus a T&M part for extensions is increasingly preferred.

To present these aspects more clearly, a tabular comparison of different cost categories is worthwhile. We thus structure all relevant factors — from initial setup costs and project management to cloud fees, ongoing updates, and training — into view.

Value Drivers in IT Modernization

For modernization to deliver tangible success, we should identify the central value drivers. After all, it is not just about replacing outdated components, but advancing the company as a whole. These value drivers include, for example, the automation of recurring processes. By digitizing routine activities, teams can invest their time in higher-value tasks, which ultimately translates into increased productivity.

Another important factor is the shortened time-to-market made possible by modern IT infrastructures. If, for example, new products or services can be introduced more quickly, the company generates revenue earlier and strengthens its market position. We recognize in this context how decisive it is to view IT as an enabler for innovation. Instead of optimizing costs alone, we should use the opportunity to open up new business areas or improve existing products.

Data utilization also plays a central role. Anyone storing sensitive data in legacy systems risks security gaps and compliance issues. Modernization can reduce such risks, for example by integrating data protection guidelines into new processes and securing the existing system landscape against potential attacks. This strengthens the trust of customers and business partners. In the mid-market in particular, we observe a growing sensitivity to GDPR and audit requirements, which are often difficult to meet in legacy environments. We have compiled further information on this in GDPR and legacy systems.

Finally, we should not underestimate cultural change as a value driver. A new IT landscape usually entails a learning curve for our teams. If we manage to design this learning curve positively, we can significantly increase the company's innovation power. New ideas often emerge from smaller pilot projects and spread throughout the company environment. According to a study by Edana, a thoughtful refactoring of software, combined with automated CI/CD pipelines, can increase the stability of overall operations, which in turn leads to positive ROI [5].

How We Calculate the Business Case

In view of the many possibly relevant individual items, a clear procedural model helps to draw up the business case for legacy-replacing IT projects in a clean way. We would like to explain in five steps how we typically proceed when calculating the ROI:

1. Define the starting situation: We begin with an inventory of the current system landscape. Which legacy systems are in use, in what condition are they, and what problems occur? We are particularly interested in maintenance costs, downtime, and manual processes that could be automated.

2. Set goals: Then we determine what is to be achieved with the modernization. Is the goal to reduce costs, open up new revenue potential, or both? This goal-setting will later help to measure success. Examples: reducing maintenance effort by 30 percent or accelerating the market launch of new products.

3. Quantify the benefit: Now it is about the monetary valuation of all potential savings as well as the qualitative gains. We typically calculate various scenarios, including a worst-case and a best-case scenario. We also take factors such as increased agility or improved customer relationships into account, insofar as they can be seriously expressed in figures.

4. Determine costs: In this step, we meticulously list all project costs. This includes planning, implementation, any outsourcing, new license fees, employee training, and operating costs. A definition of project boundaries that is too narrow is dangerous because relevant effort could fall through the cracks [1].

5. Calculate ROI and compare scenarios: Finally, we set the net gain from our benefit forecasts in relation to the investment costs. We also juxtapose various scenarios to give decision-makers a realistic outlook. This can help determine which path — for example, gradual modernization vs. a big-bang approach — has the higher ROI.

This structured approach has, in our view, proven itself in various projects: from the complete replacement of monolithic legacy systems to targeted refactoring of individual modules. On the same basis, the arguments for the business case can be plausibly and comprehensibly presented to management. It is worth monitoring progress and successes on a digital platform so that adjustments can be made quickly. Best practices also recommend continuously tracking the ROI rather than calculating it only at project start.

Best Practices from Practice

Practical examples clearly show what companies actually face in modernization projects. A classic example is the introduction of a helpdesk system that costs 50,000 euros per year and generates expected savings of 75,000 euros. Here the company proceeded after a systematic analysis and reduced the costs for manual support through automation, which directly improved the ROI [1].

Likewise, the importance of low-code platforms is rising, especially in situations where classic software development would be lengthy and expensive. An analysis showed that low-code methods require an investment of 90,000 euros but achieve an ROI of 65 percent after three years. By comparison, a more traditional development variant cost 150,000 euros and led only to an ROI of 35 percent [1]. Such examples illustrate how strongly the choice of development methods can influence project success.

Interestingly, even smaller implementations often show large effects. In a case we observed, the renewal of an ERP system with investment costs of 80,000 euros achieved annual savings of 45,000 euros — amortization in less than two years [2]. Here the company decided to phase out several legacy systems at the same time and automate many manually shaped process flows.

When we modernize legacy systems, it is also advisable to plan compliance requirements in from the outset. A popular scenario is the switch to SAP S/4HANA in the course of the SAP ECC replacement 2027. Companies that begin the migration early typically have fewer stress phases at the end of the support period. They also benefit from newer functions such as embedded analytics technologies, which enable further cost savings. Experience shows that the ROI advantage of a migration is greater the more thoughtfully and earlier you tackle the changeover.

Another success recipe consists in consistently reducing technical debt by thoroughly refactoring the code and simplifying outdated interfaces. A large portion of expensive maintenance effort is thus avoided. Edana showed in a report that technical debt is among the largest hidden cost factors and can significantly diminish ROI in the long term [5]. It is therefore worth not migrating legacy assets into new environments but cleaning them up beforehand.

Tips for Communicating with Management

For a modernization project to be approved and implemented purposefully, we have to convey the business case to management in a comprehensible and well-founded way. From our perspective, it helps to prepare the results of the ROI calculation so that even people without deep technical know-how recognize the added value. That means we create a clear, well-visualized set of figures that displays savings and gains in a structured manner.

It is also important to openly address both opportunities and risks. If we approach management too optimistically and only mention advantages, we risk losing trust later if something does not go as planned. It is better to show realistic scenarios and have constructive solutions at hand. We thus build understanding for possible delays or additional efforts that can occur in complex transformation projects.

It is also advisable to define concrete milestones and to put their measurement on the agenda. If we can lay out that after six months a certain part of the legacy systems will be replaced, that delivers tangible interim results. These stage goals illustrate how the project develops and reduce skepticism. In addition, we should emphasize how important methodical guidance — for example through internal or external expertise — is for success.

Another argument we frequently use is strategic relevance. Many CEOs and CFOs pay attention not only to savings or short-term profit but also to the ability to remain competitive in the long term. Contemporary IT infrastructure is today the key to innovation, growth, and risk minimization. By showing that modernization is in line with overarching corporate goals, we have a solid basis for investment decisions.

Finally, we recommend demonstrating to management the advantages of a pilot project in which important functions are already modernized and can deliver results quickly. Such an approach generates positive momentum and lays the basis for growing trust in the upcoming overall transformation. It is often sensible to scale or refine the pilot phase in another form later, once the leadership recognizes the potential.

Considering Funding Options and Compliance

Once it is clear that legacy system modernization is economically worthwhile, we should examine possible funding options. In Germany, certain funding programs are available to mid-sized companies, for instance, to support digitalization measures. These include KfW funding for digitalization, under which companies can in many cases secure attractive grants or favorable loans. Especially with high upfront investments, a look at financing is worthwhile to improve the ROI.

In addition to financial aspects, we must not forget compliance. Especially critical is GDPR compliance when we work with customer data or maintain international business relationships. Legacy systems are often criticized here because of their outdated security architecture. Anyone who modernizes their systems can simultaneously switch to current encryption and authentication standards, which reduces the likelihood of data protection violations. These measures increase the trust of customers and investors and at the same time protect against financial losses through possible fines.

Industry-specific regulations, such as in the financial or healthcare sector, must also be considered in modernization projects. On these topics, it can be sensible to bring in external specialists or rely on standardized platforms and certified cloud services that already meet common compliance regulations. Compliance not only ensures the smooth execution of the project but also has a positive long-term effect on the ROI, because potential fines, reputational damage, and later retrofits are minimized.

In many cases, it can be said that modernization initially implies higher expenses but at the same time brings greater funding opportunities, increased productivity, and better legal certainty. In the medium term, the ROI is therefore often higher than when trying to keep a legacy system alive truly to the last day. This insight matches the experience that companies can achieve considerable competitive advantages through cloud migrations, optimized workload management tools, or new security architectures [6].

Conclusion and Outlook

When we talk about replacing legacy systems, it is not just about a technical upgrade but a comprehensive step toward future viability. In an increasingly digitalized world, companies can hardly avoid modernizing their outdated infrastructures. The art is to make the investment decision fact-based and to estimate as precisely as possible when the project will pay off and what long-term advantages will arise. This is precisely what makes the ROI an essential tool.

This article has shown how multifaceted a serious ROI calculation must be. We have presented five central steps that range from setting goals through the precise list of costs to long-term success monitoring. Added to this are best practices from corporate practice that illustrate how strongly the result of modernization can affect revenue, organization, and innovation power. Whether we choose a big-bang approach or an iterative approach — both variants can work depending on context, as long as we keep both the benefit and the risks in equal view.

For mid-market decision-makers and budget officers, it is also relevant to structure the modernization in such a way that funding programs are sensibly integrated and compliance requirements are met. The modernization of legacy systems in mid-market companies requires the highest level of planning, because existing core processes are often closely intertwined with legacy components. A well-thought-out modernization plan also takes into account topics such as data protection, strategic orientation, and cultural change.

We are convinced that a clear commitment to modernization also sends a signal inward: a company that invests in new technologies can attract and motivate talent, while customers benefit from greater efficiency and higher quality standards. Ultimately, it is not about replacing legacy systems at any price but about creating a win-win situation in which long-term success and economic sustainability become more secure. Whether amortization occurs within two years or only after four years depends strongly on project size, industry, and individual factors.

Anyone following the steps presented here gives themselves a solid starting basis for planning the start of a modernization project as a worthwhile and well-managed initiative. We recommend continuously observing the ROI and making adjustments as needed — because even the best planning can experience unexpected changes in the fast-paced business world. With a clear view of costs, benefits, possible risks, and a methodical approach, we deliver to management an outstanding argument for why replacing legacy systems is worthwhile. IT modernization ROI thus becomes a driver for strategic development and sustainable growth.