One in four people with mental health problems in Britain report debt or arrears, which is nearly three times the rate among individuals without similar conditions. Although health professionals commonly encounter debt among patients, some report that they lack basic knowledge to effectively intervene and that patient debt is often not acted on until a crisis emerges. Our aim in this article is to improve psychiatrists’ knowledge and confidence in dealing with patient debt. We provide basic definitions of debt and problem debt; outline the impact that debt can have on patients’ health, social and financial well-being; identify the stages and signs that a patient may be accruing problem debt; describe how psychiatrists should respond; and review the instruments available to assess patients’ mental capacity to make financial decisions. We do not expect psychiatrists to become ‘debt experts’, but provide working knowledge for engaging more effectively with this problem.