Financial hurdles frequently make people forego or postpone necessary care. Therefore, targeted reductions in healthcare prices may help to improve access to essential healthcare for the poor. This paper evaluates to what extent simple behavioral incentives like letters and flyers sent to low-income groups stimulate the participation in a beneficial health insurance plan. Using a large-scale randomized field experiment we study the effect of contacting potential beneficiaries on the take-up of the Increased Reimbursement (IR) for healthcare in Belgium. In line with previous behavioral evidence, we find a substantial effect of around 15 percentage points on the take-up of IR although this effect differs strongly across regions. Moreover, we find that those who take up IR as a response to the letter are on average older, have lower historic healthcare expenditures and are less absent from work. The group that remains without IR can be considered, on average, as less vulnerable. As such, the mailing arguably succeeds in reaching out to the target population.