Operation Yellowhammer

Operation Yellowhammer is the codename used by the UK Treasury for cross-government civil contingency planning for the possibility of a no-deal Brexit. In the event of exit with no-deal, the UK's unilateral departure from the EU could disrupt, for an unknown duration, many aspects of the relationship between the UK and European Union, including financial transfers, movement of people, trade, customs and other regulations. Operation Yellowhammer is intended to mitigate, within the UK, the effects of this disruption, and would be expected to run for approximately three months. It has been developed by the Civil Contingencies Secretariat (CCS), a department of the Cabinet Office responsible for emergency planning.