This Practice Note provides an overview of UK government policy on decommissioning, ie the process for permanently removing installations and infrastructure from the seabed or securing wells. The UK’s policy on decommissioning, and its execution, is overseen by the Department for Energy Security and Net Zero (DESNZ), acting through the Offshore Petroleum Regulator for Environment & Decommissioning (OPRED). DESNZ was established on 7 February 2023 and has taken over the energy portfolio of the former Department for Business, Energy and Industrial Strategy (BEIS), which no longer exists - including its functions in respect of decommissioning. References to ‘BEIS’ within this practice note are references to historical functions of BEIS. While the UK has policy documentation, much of this policy stems from the UK’s obligations under international law. This Practice therefore also covers international law and policy that shape the UK decommissioning policy framework. What are the key international law instruments governing UK decommissioning installations regulation? The Geneva Convention on the Continental Shelf 1958 (Geneva Convention) was an early international convention