The Netherlands has adopted a formal childcare investment strategy to promote, in particular, the societal and educational integration of children from disadvantaged backgrounds. However, its particularly low-income families and families with migration backgrounds who make significantly less use of formal childcare, creating long-term inequalities for both children and parents. A key but understudied factor behind variation in formal childcare use are parents’ perceptions of childcare accessibility. It is very likely that low-income and migrant families perceive formal childcare as less accessible, for example by overestimating the costs for childcare. Research from predominately qualitative studies suggest that one of the biggest barriers to perceived accessibility of childcare is, what we call, lack of ‘system knowledge’. System knowledge refers to knowledge about the organization of a government service and related application procedures, as well as functional and digital literacy. So far, studies examining parents’ system knowledge are almost absent, thereby limiting our knowledge regarding the influence of system knowledge on perceived accessibility of formal childcare and finally, childcare behavior. We therefore propose a unique measurement of system knowledge, linking it to established measurements of perceived accessibility of childcare and childcare behavior. In combination with socio-demographic data from the LISS core panel as well as the LISS work & schooling module, the family & household module, these data will enable us to identify the main knowledge barriers to accessing formal childcare, thereby contributing to reducing inequalities among parents and children. Next to producing scientific articles, key results will be summarized in a policy brief directed at policy makers such as the Ministry of Education, Culture, and Science.