People often form intentions but fail to follow through on them. Mounting evidence suggests that such intention-action gaps can be narrowed with prompts to make concrete plans about when, where, and how to act to achieve the intention. In this paper, we pushed the notion of plan-concreteness to test the efficacy of a prompt under a minimalist automated calling setting, where respondents were only prompted to indicate a narrower duration within which they intent to act. In a field experiment, this planning prompt significantly helped people to pay their past dues and get out of debt delinquency. These results suggest that minimalist automatic planning prompts are a scalable, cost-effective intervention