In renewable energy projects, property tax has long been viewed as a relatively straightforward part of the overall structure. Based on the characteristics of an individual power plant or park, the tax level could be assessed with reasonable accuracy, and it has been taken into account in investment calculations as a well-known cost item. However, the Finnish Tax Administration’s updated guidance on the property taxation of power plants, published in spring 2026, shows that this approach is no longer always sufficient.

The updated guidance reflects a broader shift in how renewable energy projects are assessed for property tax purposes. Instead of focusing on individual installations, attention is increasingly directed towards the overall system in which electricity is generated, transmitted, and consumed. In particular, the importance of interconnections between projects is emphasised in situations where multiple operators and technologies are located within the same area or share infrastructure.

This development is concretely illustrated by the decision of the Supreme Administrative Court KHO 2024:51, which has clearly influenced the updated guidance. The case concerned when a separate property tax rate for power plants may be applied. The key issue was not the size of an individual plant or its owner, but whether multiple plants together formed a single operational entity when connected to the electricity grid.

The Court held that the so-called common connection point should not be understood narrowly as a single technical boundary. Instead, the entire grid infrastructure through which the power plants are connected to the electricity network must be taken into account. When the combined nominal capacity of several plants exceeded the statutory threshold, the application of a separate tax rate was justified, even if the plants were owned by different companies.

In practice, this ruling means that formal distinctions in property taxation give way to an assessment based on the factual overall structure. The same approach is now also reflected in the Tax Administration’s guidance.

In practical terms, the system-based approach becomes particularly relevant in projects that expand or develop in phases. A wind or solar project originally designed as an independent entity may later become part of a broader production complex through shared grid connection solutions or regional development. In such cases, the basis for property taxation may also change without any material change to the individual project itself.

This makes property tax a more strategic issue than a mere annual cost. Tax treatment may be linked to project structure, neighbouring developments, and grid connections in ways that are not always obvious unless the overall system is considered already at the planning stage.

As property taxation increasingly relies on functional overall systems, attention inevitably also turns to energy storage. Battery storage facilities are a rapidly growing part of the renewable energy landscape, and they are increasingly being integrated into the same infrastructure as wind and solar power plants. Despite this, the updated guidance does not explicitly address the property tax treatment of battery storage facilities.

This raises an important question: if property taxation is assessed on an overall basis, what is the position of battery storage within this framework? Are they part of a power plant, independent structures, or something in between? And how does their presence affect the taxation of the overall system when they are connected to the same grid solution as generation assets?

Since the guidance does not provide clear answers, the assessment of battery storage continues to rely on general principles and case-by-case evaluation. This leaves operators with the responsibility to determine how storage fits within the broader property tax framework.

The updated guidance and the underlying case law do not make property taxation unpredictable, but they do change the way predictability is achieved. The final tax outcome is no longer determined solely by individual plans and figures, but also by the broader system in which the project is situated. This is particularly relevant for projects where generation and storage are integrated into the same infrastructure.

For this reason, it is advisable to address property tax questions at the stage when project structure, grid connections, and potential storage solutions are being decided. When property tax is determined on an aggregate basis, the role of battery storage within that system should also be assessed early on.

At Svalner Atlas, we aim to support you and your business with tax matters related to renewable energy. You are also welcome to contact us if you have questions regarding property taxation or taxation more generally.

We have comprehensive expertise in the planning and implementation of renewable energy projects as well as in various areas of tax and legal advisory. We assist companies and individuals in a client-oriented manner in finding the best solutions for their specific situation, taking into account evolving regulation and current case law. We are happy to discuss our services in more detail.