The Carbon Reduction Commitment's 90 percent emissions rule, otherwse known as the 'flexible de minimis' rule, requires all particpants to account for at least 90% of their total carbon footprint emissions. The 90% rule aims to focus attention on the largest, and most cost effective, opportunities to reduce carbon emissions.

The 90% emissions rule can include all energy reported through the Climate Change Agreement, European Union Emissions Trading Scheme, as well as all 'Core Sources' of non-transport energy consumption.