This Practice Note is a ‘how to’ guide setting out the key steps and considerations for local authorities assessing the age of an asylum-seeker or migrant to determine eligibility for statutory support and duties owed under the Children Act 1989 (ChA 1989). It sets out the key parties involved in an age assessment, the key elements of a lawful local authority age assessment, evidence requirements, common risks, pitfalls and consequences of a successful challenge.What is an age assessment?An age assessment is the process by which a decision-maker, usually a Home Office assessor or a local authority social worker, establishes the chronological age of an asylum-seeker or migrant in order to determine their eligibility for statutory support including whether they are owed duties under ChA 1989. It is a crucial step in the asylum process.For background reading, see Practice Notes: Age assessments—immigration and asylum, Local authority duties towards unaccompanied asylum seeking children and Asylum seekers with children under 18 and unaccompanied asylum seeking children who reach 18.Why