This study is the first large-scale empirical account of child maintenance non-compliance in Sweden. The scheme explored is the guaranteed support system, i.e. when liable parents do not comply with their formal maintenance obligations as determined by the Swedish Social Insurance Agency (SSIA). The objective is to map out and describe the overall reasons why parents do not pay, as well as to explain why parents’ perceptions of their maintenance obligations diverge from those of the SSIA officials. To this end, the study utilises both quantitative descriptive analysis and qualitative thematic text analysis. The data were built on a unique body of material comprising over 700 court cases where liable parents disputed their maintenance obligations in Sweden’s 12 administrative courts, during 2014–2019. The quantitative results show that claiming economic inability and regular involvement in the care of children are the two most common arguments for non-payment. The qualitative analysis further suggests that the administrative tools and legal assessments designed to calculate payments to aid parents are in reality creating barriers, uncertainty, and distrust in the process. Consequently, the rules designed to protect children in lone-parent households are a factor contributing to non-payment by the other parent. The article concludes with reflections and public policy implications.