This Practice Note outlines the legal framework underpinning the duty of UK immigration decision-makers, including the Home Office, tribunals and courts, to safeguard and promote the welfare of children when making decisions affecting them. It discusses relevant provisions of the UN Convention on the Rights of the Child, s 55 of the Borders, Citizenship and Immigration Act 2009 (the s 55 duty) and the Charter of Fundamental Rights of the European Union as well as the scope and application of the duty and the consequences of a failure to address the duty.