Almost all parents lie to their children, and recent studies warn that parental lying may negatively impact children's trust in their parents. However, perspectives of children on parental lying and its effect on trust in parents have rarely been studied. In the current manuscript, we (1) report the development and co-creation of an age-appropriate instrument to assess children's perspectives on parental lying in middle childhood (8- to 12-year-olds), (2) investigate in a pilot sample (n = 62 Dutch 8- to 12-year-olds) whether the instrument is able to capture children's perspectives on parental lying and truth telling, and (3) explore children's perspectives on parental lying and trust. Three different lies were distinguished: lies to benefit the parent, lies to benefit the child, and prudential lies. The instrument was co-created with a child panel (n = 5 Dutch 8- to 12-year-olds) and a game designer. The instrument was deemed age-appropriate based on the high percentages of correct classifications of parental lies and truths. Our results demonstrated that children evaluated child-benefit and prudential parental lies more positively than liar-benefitting parental lies. Children expected trust to be lower when a parent used a liar-benefitting lie as compared to a child-benefitting lie. Our results demonstrated that 8- to 12-year-olds already have differentiated opinions about different types of parental lies and how they can affect trust, and our open-access instrument provides an engaging and age-appropriate opportunity for future research into children's views on parental lying and its effect on trust.