1.This instrument makes operational changes to the UK Emissions Trading Scheme (UK ETS). These include allowing operators to apply for changes to free allocation in 2022 based on their activity levels in 2019 and 2021, omitting 2020, if they can demonstrate a discrepancy of at least 15% between reductions in output and emissions caused by the COVID-19 pandemic. The instrument also provides Hospitals and Small Emitters (HSEs) with an opportunity between January and March 2023 to re-enter the main UK ETS from 2024 onwards. This recognises that operators made the decision to apply to be HSEs when expecting rules under the EU Emissions Trading System rather than the UK ETS. HSE operators who re-enter the main ETS in this way are eligible for free allocation if they applied successfully for free allocation in previous years. The instrument also applies updated Global Warming Potential values (GWPs), as agreed at COP 24 and COP 26. GWPs allow comparisons of the global warming impacts of different gases by measuring how much energy the emissions of one tonne of a gas will absorb over a given period of time relative to one tonne of CO2.