Background: Primary caregivers of people with disability provide extensive physically and emotionally demanding care. Objectives: The aim of this study was to quantify the burden of high psychological distress in primary carers of people with disability and identify modifiable factors in relation to high psychological distress. Methods: The 2015 national 'Survey of Disability, Ageing and Carers in Australia' was used to derive a nationally representative sample and estimate weighted prevalence rates of high psychological distress (Kessler scores >=22) in primary carers of people with disability. Risk factors were evaluated using weighted logistic regression models with lasso techniques. Results: Approximately 27% of carers had high psychological distress. Nearly half of the study population reported changes in their health and wellbeing. A delay in general practitioner (GP) visits was common and associated with >2-fold increase in risk of high psychological distress. Discussion: The findings suggest targets for early diagnosis and intervention, and adequate referrals from GPs to meet the health needs of carers.