Purpose <p>Successful completion of processes within the social insurance system depends on both individual characteristics of work disability applicants and structural characteristics of the system itself. The interaction between individuals’ knowledge and abilities and the comprehensibility of the system constitutes what is referred to as social insurance literacy (SIL). Limited SIL may lead to feelings of injustice or unfairness. The aim of this study was to examine the associations between SIL and perceived justice and fairness among clients applying for work disability benefits.</p> Methods <p>A cross-sectional survey study was conducted among clients applying for work disability benefits within the Dutch social insurance system. Data were collected on the four domains of SIL (individuals’ ability to obtain; to understand; to act; and system comprehensibility), and on perceived justice and perceived fairness. Associations were analyzed using multivariable linear regression.</p> Results <p>A total of 168 respondents were included in the sample. Of the four SIL domains, clients’ self-reported ability to act on information was significantly associated with perceived justice [<i>B</i> = 0.26, SE = 0.12]. In addition, system comprehensibility was significantly associated with both fairness [<i>B</i> = 0.57, SE = 0.08] and justice [<i>B</i> = 0.72, SE = 0.09]. No significant associations were found for the domains related to the ability to obtain or understand information.</p> Conclusion <p>System comprehensibility was more strongly associated with perceived justice and fairness than clients’ individual abilities to obtain, understand, or act on information. Improving the clarity and accessibility of information provided by the system may be an effective strategy to enhance clients’ perceptions of justice and fairness when applying for work disability benefits.</p>