The European Commission has adopted a Communication on the total number of allowances in circulation (TNAC) on the European carbon market, with a total of 1,111,736,535 in 2023. This is the first Communication on the TNAC since the operation of the Market Stability Reserve (MSR) was amended as part of the ‘Fit for 55’ legislative package, revising Decision 2015/1814 (MSR Decision) and Directive 2003/87/EC (EU Emissions Trading System Directive (ETS Directive)), and the change laid out in Regulation (EU) 2023/435 (REPowerEU Regulation) in February 2023, as one of EU's response to the energy crisis. If the threshold of 1.096bn is exceeded, 24% of the total allowances are to be placed in reserve under the MSR decision, and a total of 266,816,768 allowances will be placed in the MSR from 1 September 2024 to 31 August 2025. Under Article 1(5a) of the MSR Decision, any allowances in the MSR above 400m allowances are no longer valid from 2023 onwards. The TNAC indicator will be published on 1 June 2025.