Non-take-up (NTU) in poverty policy is generally designated as individuals who are entitled to public assistance but do not benefit from it.Many public assistance policy-related factors result in NTU. According to van Oorschot (1996), typical factors affecting NTU are negative attitudes toward welfare benefits, insufficient knowledge of the welfare scheme, degrees to which individuals understand information, expectations of low benefits, uncertainty about eligibility, and policy complexity. Nevertheless, more analyses should be conducted on how policy complexity and ambiguity influence potential public assistance applicants because of the insufficient academic concern regarding attitudes and behaviors when considering applying for public assistance. Even qualified citizens might abandon their claim to benefits when social policy is complex and ambiguous. The National Basic Livelihood Security Scheme (NBLSS), the general public assistance scheme in South Korea, has such a complex design that many citizens do not comprehend whether they are eligible for the policy, even after consulting local authorities.Although the literature on the relationship between the NBLSS and NTU constantly argue that rigorous and entangled elements in eligibility criteria make the issue of NTU worse in South Korea (for example, Ku & Baek, 2008;Park, 2008), essential features of the institutional complexity have been largely unexplored.This article raises and empirically tests a critical research question in the sphere of social policy and behaviors (or attitudes): Do complexity and ambiguity affect the intent to apply for public assistance? To answer the question, this study utilizes a large-scale of online survey method, which significantly differs from previous experiment-based approaches with small-group poor participants. The alternative challenge furthers to understand how the public and the poor might behave when they take account of applying for means-tested welfare programs. Recently, more categorical public assistance schemes came into force such as the basic pension scheme for the elderly and the disability pension scheme for people with severe disabilities in Korea. In the circumstances, this issue would grow more important in the public assistance, because,