Decarbonisation will involve a significant restructuring of the European economy. Targeted government expenditure is set to reach unprecedented levels, and taxation systems are being redesigned. Alongside decarbonisation, macroeconomic policy must retain its core goal of supporting sustainable economic growth. Existing ‘Growth & Stability’ pact rules, when restored in 2023, are likely to place limits on government expenditure owing to high debt levels. This panel will discuss the concept of a ‘green golden rule’: should targeted climate expenditure be excluded from contributing toward maximum debt levels. More broadly, what are best principles for coherent fiscal policy to maximise decarbonisation impact and sustain long-term economic growth?