An emerging body of research suggests that temporal processing may be disrupted in autistic children, although little is known about behaviours relating to time in daily life. In the present study, 113 parents of autistic and 201 parents of neurotypical children (aged 7–12 years) completed the It’s About Time questionnaire and open-ended questions about their child’s behaviour relating to time. The questionnaire scores were lower in the autistic compared with the neurotypical group, suggesting that behaviours are affected. Three key themes were identified using thematic analysis: autistic children had problems with temporal knowledge, learning about concepts relating to time, such as how to use the clock and language around time. There were differences in prospection with autistic children having more difficulties with how they thought about the future and prepared themselves for upcoming events. The final theme, monotropism, described how autistic children viewed their time as precious so they could maximise engagement in their interests. The present study indicates that behaviours relating to time can have a considerable impact on the daily lives of autistic children and their families. Further work exploring the development of temporal cognition in autism would be valuable for targeting effective educational and clinical support. Lay abstract Many everyday activities require us to organise our behaviours with respect to time. There is some evidence that autistic children have problems with how they perceive and understand time. However, little is currently known about this, or the ways in which behaviours related to time are impacted in daily life. In this study, 113 parents of autistic children and 201 parents of neurotypical children completed a questionnaire and open-ended questions about their child’s behaviour relating to time. Questionnaire scores were lower in the autistic group compared with neurotypicals, which suggests that behaviours relating to time are affected in autistic children. The open-ended responses further confirmed that the autistic children struggled with time and that this impacted on them and their family. Three key themes were identified. Theme 1: autistic children have problems with learning about concepts relating to time such as telling the time from a clock and using words to describe time (hours, minutes, etc.) appropriately. Theme 2: autistic children think about the future differently. Planning and working under time pressure were described as a problem. Theme 3: autistic children have strong interests which take up a lot of their attention and worrying about having sufficient time to pursue these interests causes anxiety. This research indicates that behaviours related to time can have a considerable impact on the lives of autistic children and that targeted support may be required.