This report by the Labour Exploitation Advisory Group (LEAG) explores the barriers documented and undocumented migrants face reporting workplace abuse and exploitation to the police and labour inspectors in the UK. It introduces a detailed framework to analyse how information about peoples’ immigration status becomes available to the Home Office following workers’ interaction with police and labour market enforcement agencies. It builds on international examples to provide practical recommendations to government, police and labour market enforcement agencies on introducing and strengthening secure reporting systems to identify and prevent labour exploitation.