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Dealing with climate change – and with the other pressing issues of sustainability requires a budgetary response. The OECD has been working with Member Countries to identify and share best practice – notably through the Paris Collaborative on Green Budgeting. For the INTOSAI Working Group on Environmental Auditing, Green Budgeting is a useful perspective in the Work Plan 2023-2025 project on Green Fiscal Policy Tools.
Green budgeting is a budgetary planning strategy which evaluates the impact of environmental costs and benefits when making budget decisions. It requires assessing the long-term economic risks associated with environmental and climate issues. This strategy guides budgeting decisions towards more sustainable investments and policies, focusing on creating mutual benefits for both the economy and the environment. For instance, green budgeting strategies may include spending on green infrastructure, energy efficiency measures, incentivising sustainable production and consumption, cleaner transport, and investing in R&D for renewable energy. In 2022, two-thirds of OECD countries had implemented green budgeting mechanisms (24 out of 36), compared to 14 out of 35 countries in 2021 (+40%). The most prevalent budgetary tools refer to carbon pricing mechanisms (22 countries, + 83% compared to 2021), environmental impact assessments (18 countries, + 33% compared to 2021), and green tagging (13 countries, +41% compared to 2021)[1].
Supreme audit institutions (SAIs) are responsible for conducting independent, objective audit and reporting activities on how public funds are being used. In an effort to promote better public financial management and improve the accountability of governments, the role of SAIs in green budgeting processes and implementation has been growing significantly but still needs to be strengthened.
Several SAIs carry out environmental and climate audits on thematic topics, but few of them on green budget expenditure. In France, the SAI published a report on the government’s green budget in 2023. It explains that France is rating its budget expenditure granularly, but that this tool can be improved and has limits. In Italy within the Green Bond Framework, independent auditors verify green spending targets financed by green bonds. In 2022, the European Court of auditors also published a report proposing recommendations on the European Union green budget statement and is currently auditing the green tagging in the EU recovery instrument (NGEU) to assess its alignment with and contribution to the European Green Deal objectives on climate action.
SAIs play a key role in the implementation of green budgeting processes in three main areas.
The involvement of SAIs in the green budgeting process is becoming increasingly important as governments attempt to shift spending to support more sustainable economies. SAIs can help ensure public funds are being used to promote sustainability, accountability and effectiveness in green activities by providing effective oversight and assurance. However, SAIs face a number of challenges in strengthening their review of green budgeting initiatives:
SAIs can reduce the challenges they face when auditing green budgeting processes and implementation by taking a series of proactive measures.
By Margaux Lelong, Policy Analyst at the OECD
Margaux-Lucrèce Lelong, is a French Senior Civil Servant and Policy Analyst at the OECD, specialising in PFM and Green Budgeting. Before joining the OECD, Margaux was a financial magistrate and external auditor for the UNESCO and the WFP within the French Supreme Audit Institution. She then joined the French Ministry of Finance where she was working on PFM issues and the Green Budget. She also worked for the IMF and WB as a PFM expert. She holds two master’s degrees from Sciences-Po and the University Sorbonne (France) where she has been teaching Public Finance and Budgeting since 2015.
[1] OECD, Government at a glance 2023

