Objective The aim of this study was to quantify the direct and indirect costs of asthma and allergic rhinitis (AR) for 2018 in Tasmania. Methods We used publicly available data, and Tasmanian-specific values where available, to estimate direct and indirect costs of both diseases. Direct costs included outcomes such as emergency department (ED) presentations, hospitalisations, general practice visits and medication use. Indirect costs included premature mortality and lost productivity. Results Direct health impacts for both conditions combined included 1454 ED presentations, 682 hospitalisations, 72446 general practice visits and 7122 specialist visits. Indirect health impacts included 13 deaths and between 483000 and 2.8 million days of lost productivity. Total costs ranged between A$126.5 million and A$436.7 million for asthma and between A$65.3 million and A$259.7 million for AR. Per-person annual costs ranged between A$1918 and A$6617 for asthma and between A$597 and A$2374 for AR. Conclusions The main financial burden due to asthma and AR was related to productivity losses from presenteeism and absenteeism. The magnitude of the economic impacts of AR and asthma warrants further analysis to produce a national-level assessment. Such analyses could identify cost-effective interventions that produce highest benefits for the management of these conditions in our community. What is known about the topic? Allergic respiratory diseases, and particularly asthma and AR, pose a significant health burden, with effects including asthma-related hospital admissions, significant pharmaceutical expenditure and lost workforce and school education productivity. Australia, and particularly Tasmania, has a high prevalence of these conditions, but no recent studies have appraised or estimated their health impacts and costs. What does this paper add? This paper proposes a unique and transparent costing model that allows the costs of these conditions to be estimated while accounting for restrictions in data availability. The model is used to provide the first comprehensive costings of asthma and AR in Tasmania, Australia. We identified that the estimated health costs are dominated by productivity losses from presenteeism and absenteeism, and that total per person costs are higher for a person with asthma compared to one with AR. What are the implications for practitioners? This analysis has the potential to guide cost-effective interventions by identifying where the highest benefits may be obtained when managing these conditions in our community.