Autistic individuals with intellectual disability are at greater risk of experiencing anxiety than their non-autistic peers without intellectual disability. Anxiety in this group may present as behaviour that challenges, often leading families to reach out to healthcare or support services. However, many families experience difficulties accessing services and, due to the lack of research into evidence-based anxiety interventions for people with intellectual disability, may not receive individualised support once in a service. This study explored caregivers' experiences of accessing services for autistic individuals with intellectual disability, and their considerations when developing new interventions for this population. Interviews and focus groups were completed with 16 caregivers of autistic people with intellectual disability. Reflexive thematic analysis was used to develop five themes about service access experiences, and three themes about caregiver considerations for anxiety interventions. Caregivers reported that their experiences of accessing services did not meet their expectations, and considerations for future anxiety interventions were often reflective of this. Interventions being flexible to family circumstances to aid accessibility, the embedding of peer support in services, and skills that can be generalised across the lifespan could be applied when aiming to improve outcomes and develop interventions for this under-served population.