Health inequalities and user financial incentives to encourage health-related behavior change are two topical issues in the health policy discourse, and this article attempts to combine the two; namely, we try to address whether the latter can be used to reduce the former in the contexts of the United Kingdom and the United States. Payments for some aspects of medical adherence may offer a promising way to address, to some extent, inequalities in health and health care in both countries. However, payments for more sustained behavior change, such as that associated with smoking cessation and weight loss, have thus far shown little long-term effect, although more research that tests the effectiveness of different incentive mechanism designs, informed by the findings of behavioral economics, ought to be undertaken. Many practical, political, ethical, and ideological objections can be waged against user financial incentives in health, and this article reviews a number of them, but the justifiability of and limits to these incentives require more academic and public discourse so as to gain a better understanding of the circumstances in which they can legitimately be used.