Background: Implementation of routinely collected patient-reported outcome measures (PROMs) ensures patients' priorities are at the forefront of care planning and helps to standardize approaches to quality improvement. In palliative care, barriers to PROMs are widely known but what are not understood are the clinical and care settings in which patients are more likely to report and when proxy reporting is needed. Objective: To examine the incidence of patient-reported symptom distress compared to the incidence of proxy reporting in palliative care and influencing factors. Methods: A national observational study using routinely collected PROMs data with influencing factors investigated by logistic regression modelling. Participants were patients with an advanced life-limiting illness receiving palliative care in an inpatient or a community healthcare setting in Australia. Results: Sixteen thousand one hundred and fifty-eight reports of symptom distress were collected from 1117 patients seen by 21 palliative care services. The majority of respondents were diagnosed with cancer (76%), were older (≥65 years, 72%) and had nominated English as their first language (88%). The majority of symptom distress reports were completed by patients (61%). The odds of a patient providing a self-report where grater when they were receiving community versus inpatient palliative care (odds ratio (OR): 3.0; 95% confidence interval (CI): 2.25-4.01), for patients diagnosed with malignant versus non-malignant disease (OR 1.7; 95% CI: 1.26-2.31), and for those who required an urgent change in their care plan versus those whose symptoms and problems were adequately managed (OR: 1.38; 95% CI: 1.04-1.83). Conclusion: Three factors are associated with an increased likelihood of patient versus proxy reporting in palliative care: healthcare setting, diagnosis, and the acuity and urgency of the patient's clinical needs. PROMs are feasible in most clinical scenarios in palliative care, including when an urgent clinical response is required.