This paper examines the implications of labour migration models that rely on employer sponsorship. According to UK government proposals, long-term migration into high-skilled jobs after Brexit will require workers to be sponsored by employers, while workers in low-skilled and low-wage jobs will receive short-term work permits that do not require an employer sponsor. The paper argues that choosing employer sponsorship over worker-driven routes has three key effects: it gives the government greater ability to regulate which jobs migrants fill; it gives employers more power over their workforce; and it increases the administrative burden associated with hiring workers from overseas. This implies that in high-skilled jobs, employer sponsorship is likely to improve the skill composition of labour migrants but reduce the total number of skilled workers admitted; and that in low-skilled positions the government faces a trade-off between the ability to channel workers to specific jobs (including those where employers struggle to attract workers) and the risk of increasing underpayment or exploitation.