Socioeconomic status (SES) is an established risk factor for poor cardiovascular outcomes, with atrial fibrillation (AF) a major contributor to cardiovascular morbidity and mortality. To examine associations between SES, clinical outcomes and access to guideline-directed therapies in patients attended by emergency medical services (EMS) with a prehospital AF diagnosis within a universal healthcare setting METHODS: We conducted a population-based cohort study of consecutive adults attended by EMS for AF across Victoria, Australia (January-2015-June-2019). Patients were stratified into SES quintiles using census-based postcode indices. Primary analysis included 14,987 patients, median age 76 (Q1-Q3:67-84), 43% male. Time-to-event-analysis demonstrated a gradient of lower rates of outpatient cardioversion and ablation and increased EMS re-presentations and mortality amongst lower SES groups. On multivariable analysis compared with the highest SES quintile, the lowest SES group was associated with reduced cardioversions (aHR 0.73(0.61-0.86), p<0.001) and ablations (aHR 0.48(0.39-0.60), p<0.001) and higher risk of EMS re-presentation for AF within 30 days (aOR 1.61(1.19-2.17), p=0.002) and over median 2.1-year follow-up (aHR 1.18(1.03-1.36), p=0.019). Mortality was also higher at 30 days (aOR 1.68(1.31-2.15), p<0.001) and over median 2.1-year follow-up (aHR=1.42(1.28-1.58),p<0.001) compared to the highest SES group. In a competing-risk model treating death as a competing event, re-presentation effect estimates remained directionally similar but attenuated and no longer statistically significant. The lowest SES groups compared to the highest were associated with reduced access to cardioversion and ablation following index attendance, along with more frequent EMS re-presentations for AF and higher mortality within 30 days and long-term follow-up.