Noora Ahonen

Senior Associate, Member of the Finnish Bar, M.Sc. (Econ.)

I advise our clients on a wide array of domestic and international tax matters. I joined Castrén & Snellman in 2021. Before joining Castrén & Snellman, I worked, among other things, as a tax specialist in the Finnish Tax Administration, as a judge of the administrative court, as tax consultant for a major auditing firm and as a lawyer at another Finnish law firm. I have, therefore, worked with a wide range of tax matters concerning both private persons as well as domestic and international organisations and gained valuable experience in handling tax matters in the Finnish Tax Administration and in the administrative courts.

In addition to my law degree, I hold a Master of Science in Economics. I have also completed court training, i.e. I have appointed as a lawyer trained on the bench.

Latest references

We advised UK-based investment company Downing in its acquisition of the entire share capital of Tornionlaakson Voima Oy. Tornionlaakson Voima owns three hydropower plants in the Tengeliönjoki river system – the Portimokoski power plants in Ylitornio, the Jolmankoski power plants in Raanujärvi and the Kaaranneskoski power plants in Sirkkakoski. The power plants produce a total of approx. 45 gigawatt-hours of electricity per year. Tornionlaakson Voima’s daily operations will continue normally, and the transaction will not affect customers. The consummation of the transaction is subject to the approval of the Ministry of Economic Affairs and Employment. Downing has over 35 years’ experience in providing a wide range of investment solutions to the needs of institutional investors, advisers and retail investors. The company manages over £2 billion in assets in both the private and public markets and its current hydro power portfolio includes approx. 50 hydro power plants in the Nordics. 
Case published 27.3.2026
We are acting as the joint legal advisor to Oomi Oy and Lumme Energia Oy in a transaction whereby Lumme Energia will merge with Oomi. As from the completion of the merger, the combined entity will be the largest electricity retail and service company in the Finnish market. In 2024, Oomi reported a turnover of EUR 373.9 million and had approximately 110 employees. Lumme Energia’s turnover for the same year was approximately EUR 314.6 million and it had approximately 50 employees. The transaction is primarily driven by the recent developments in the electricity market and the strategic goal to develop competitive products and services. Another key objective is to further enhance the customer experience, which is a shared value between the two companies. As a result of the merger, Lumme Energia’s customers will transfer to Oomi, and Lumme Energia will become one of Oomi’s shareholders. The completion of the transaction is subject to an approval by the Finnish Competition and Consumer Authority.
Case published 29.8.2025
We advised Jefferies as the sole arranger and lead manager in a transaction in which Finnfund, a Finnish development financier and impact investor, issued a EUR 100 million green bond. The 10-year bond bears interest at the rate of 3.5% per annum. The bond offering was placed to international investors, including a portion of dedicated green bond investors/portfolios. The bond represents Finnfund’s first ever green transaction and second issuance under its Sustainability Bond Framework established in September 2022. The proceeds from the issue will be used in accordance with the green project categories of Finnfund’s Sustainability Bond Framework to finance and/or refinance eligible green lending, equity investments, and mezzanine financing mainly targeting, for example, the objective of climate change mitigation and adaptation and/or environmentally sustainable management of living natural resources. Net proceeds will be allocated to eligible projects with the objective to mobilise debt capital to support Finnfund’s mission to generate lasting impact by investing in businesses that solve global development challenges. In addition, it contributes to Finnfund’s goal to foster sustainable development by providing investment opportunities for private investors. In its strategy, adopted in January 2022, Finnfund sets one of its targets to fund 50% of its investments with private capital by 2030. Mobilising private capital is key to achieving the UN Sustainable Development Goals (SDGs) in developing countries, given that the UN estimates the financing gap at USD 2.5 trillion per year. Jaakko Kangasniemi, Managing Director, CEO at Finnfund said: “Sustainable, innovative businesses and investors play an integral role in solving both global and local challenges, such as climate change mitigation and adaptation, and biodiversity loss. Capital markets are also vital in the transition away from fossil fuels. We are glad to have such a strong support for our impact investing activity and our mission to foster sustainable development and green transition.” Andrey Medvedev, Senior Vice President at Jefferies said: “We are delighted to have assisted Finnfund issuing its longest private placement to date and showcasing its innovative green projects. This deal demonstrates Finnfund’s appeal to a diversified international investor base and cements its position as a leading development financing agency.”
Case published 26.1.2024
We successfully represented a Finnish construction management consultancy and a safety coordinator employed by the company in criminal proceedings concerning an alleged occupational safety and health offence. The prosecutor sought a penalty for an alleged breach of occupational safety regulations. The charge arose from a fall accident at a construction site where our client acted as the safety coordinator appointed by the developer. We assessed the scope of the safety coordinator’s duties in relation to the responsibilities of the main contractor, as well as how our client had fulfilled their obligations in practice. We demonstrated that our client had acted with due care and in full compliance with their duties throughout the planning, preparation and execution of the construction project. The District Court of Eastern Uusimaa dismissed the charge against our client. The Court held that our client, in their capacity as safety coordinator, had duly fulfilled the occupational safety obligations incumbent on the developer during the planning and preparation phases of the construction project and had not been aware of the fall protection deficiency identified at the site. The judgment is final insofar as our client is concerned.
Case published 22.6.2026
We advised Efima Oyj on the sale of its financial management services business to Rantalainen as part of its strategic focus on fully concentrating on the delivery of business applications as well as data and AI solutions. As a result of the transaction, customer contracts related to financial management services and 65 experts working in these services will transfer to Rantalainen. The transaction will be carried out as a transfer of business, and the experts will move to the new owner as existing employees. Efima is a Finnish digital company that supports the sustainable growth of large and mid-sized companies by streamlining their business processes and by creating competitive advantage through the innovative use of artificial intelligence and data. The company has nearly 200 experts based in Helsinki and Tampere.
Case published 12.6.2026
We advised lead investor Ugly Duckling Ventures on the EUR 6.5 million funding round of Skyfora. The round also included Eviny Ventures, LUMO Labs and EIC Fund, alongside non-dilutive funding from Business Finland. The investment will support the commercial scale-up of Skyfora’s weather intelligence solutions, the expansion of partnerships with telecom operators, forecasting providers and meteorological institutions, and the continued growth of the team. Skyfora is a Finnish company developing high-resolution weather data solutions using patented technology that extracts atmospheric data from GNSS receivers embedded in existing infrastructure, such as telecom networks. By unlocking previously untapped data sources, Skyfora enables the next generation of AI-driven weather forecasting and supports improved decision-making across weather-sensitive industries. Ugly Duckling Ventures is a Copenhagen-based venture capital firm focused on early-stage Nordic B2B technology companies, with an emphasis on medtech, resilience tech and business services.
Case published 10.6.2026
castren snellman general atlantic iceye
We advised General Atlantic as the lead investor on ICEYE’s EUR 1 billion series F funding round, valuing the company at over EUR 10 billion. ICEYE raised EUR 450 million (USD 520 million) in a primary Series F funding round led by General Atlantic. Additional investors included Solidium, Tesi, Varma, Ilmarinen, Lifeline Ventures, Nokia, Qatar Investment Authority (QIA) and TCV. Together with a secondary placement, the total fundraising exceeds EUR 1 billion. ICEYE is the world leader in sovereign intelligence from space, providing continuous monitoring capabilities to detect and respond to changes in any location on Earth. The company operates the world’s largest and most advanced Synthetic Aperture Radar satellite constellation. General Atlantic is a leading global investor with more than four and a half decades of experience providing capital and strategic support for over 885 companies throughout its history. As of March 31, 2026, General Atlantic manages approximately USD 126 billion in assets across its investment strategies. We advised General Atlantic on this transaction in collaboration with the international law firm Paul, Weiss, Rifkind, Wharton & Garrison.
Case published 9.6.2026
We advised Oomi Solar Oy on the sale of a solar power park and battery energy storage project to Tuulipolar Oy. The transaction concerned a 24 MWp solar power plant and a 36 MW / 70 MWh battery energy storage system (BESS) to be constructed in Tornio. Tuulipolar Oy will act as the owner and operator of the plant, while Oomi Solar Oy will be responsible for its design and construction. The project will form the world’s northernmost industrial hybrid power plant, contributing to Finland’s green energy transition by increasing renewable energy production and electricity storage capacity in Northern Finland. The hybrid solution enables optimization of production as well as active participation in electricity markets and reserve services, improving the project’s profitability and supporting the balance of the electricity system year-round. Electricity production from the hybrid plant is expected to begin in 2028. Oomi Solar Oy is a Finnish renewable energy expert with experience from nearly 200 MW of installed solar capacity. The company helps businesses and communities accelerate the green transition by offering comprehensive solutions, including solar power plants, energy storage systems, and related lifecycle services from project development to maintenance. Oomi Solar Oy employs more than 20 energy professionals and delivers solar power projects across Finland. The company’s vision is to be Finland’s most desired partner for solar energy and energy solutions.
Case published 5.6.2026