Aggressive tax planning is an increasing source of concern for governments. Hybrid mismatch arrangements using hybrid entities, instruments and transfers using different tax treatment in two states may significantly reduce overall tax for taxpayers. Although countries are free to choose how to set up their tax system, the OECD Committee on Fiscal Affairs prompts member states to examine such arrangements and has recently released a report on hybrid mismatch arrangements. The report describes the most common types of such arrangements and the effects they aim to achieve. It summarises the tax policy issues raised by these arrangements and describes policy options to address them. The report concludes that the same concern existing in relation to distortions caused by double taxation exists in relation to unintended double non-taxation, as well. Therefore, the OECD recommends several actions to its member states. Stefan Bendlinger presents a summary of the report with a focus on actions that have already been introduced into Austrian tax laws to combat hybrid mismatch arrangements.