People with mental health problems (MHPs) in Britain are nearly three times more likely to report debt compared with individuals without similar conditions. With one-in-four respondents with MHPs reporting personal debt, this may be equivalent to eight or nine clients in the recommended national community mental health nurses' (CMHNs) caseload of 35. Although client debt is not a new problem for CMHNs, it can pose significant difficulties for client well-being and nursing practice. This paper reviews the published literature on debt and mental health, then considers three of the challenges that client debt can present to: (1) nursing knowledge--moving away from understandings of client debt based on crisis, and towards those focused on process and prevention; (2) nursing practice--reworking the collaborative relationship between CMHNs and external debt advice agencies; and (3) nursing identity--managing the role conflicts that engaging with client debt can bring. The paper concludes by contending that nurses should raise and monitor debt issues among clients, but cannot be expected to become proxy 'debt advisors', with CMHNs being encouraged to increasingly collaborate with debt advisors (rather than simply referring on clients).