OBJECTIVES: Patients' time spent receiving care incurs an opportunity cost, which ought to be considered when conducting an economic evaluation from a societal perspective. Instruments for capturing time-related costs are presently lacking, especially for children and young people (CYP). To address this gap, we developed and pre-tested the Children and Young People's Time-Use Questionnaire for use in Economic Evaluation (CYP-TUQEE), producing versions for direct completion by CYP aged 11-17 years, and proxy completion by parents/carers of CYP aged up to 10 years. METHODS: The CYP-TUQEE was developed using an iterative process involving scoping reviews, consultation with a Working Group of experts, and pre-testing through think aloud interviews with 20 CYP and nine parents/carers. This process aimed to produce a comprehensive, adaptable questionnaire that is not onerous to complete by CYP or parents/carers within the target age ranges. RESULTS: Participants engaged well with the think aloud process, and provided feedback to inform the development of a novel, standardised instrument to facilitate the collection and inclusion of time-use data for paediatric economic evaluations. Feedback indicates that the CYP-TUQEE is easy to complete, clear, and ready for additional validation. CONCLUSIONS: The CYP-TUQEE addresses a prominent gap by providing an accessible tool for data collection, tailored to CYP. Inclusion of patient time costs can assist in decision-making and ensure prioritisation of interventions respectful of patients' time. Future research will involve additional testing of the CYP-TUQEE in a real-world setting for further validation and refinement, and elicitation of a 'unit cost' (value) for CYP's time.