This article addresses a growing social and legal debate around healthcare provision for gender diverse children. Temporality is used as a theoretical lens to highlight how biological determinism has informed legal approaches to gender diverse children in a series of recent cases. In these cases, accounts of sex and gender as temporally linear are troubled by gender diverse children whose gender does not arise ‘inevitably’ from their sex. The Court’s reaction to this conflicts with recent shifts in healthcare which have begun to reframe the temporal pathways from childhood to adulthood away from singular towards multiple futures where gender is capable of being both ‘paused’ and ‘reversed’. Law’s commitment to ‘linearity’ and ‘permenance’ in its conceptions of the temporality of childhood are a key but emerging locus in the reinforcement of heteronormative temporalities downplaying contemporary harms to the child in favour of speculative future harm.