The British Axial Spondyloarthritis Cohort (BAxSIC) study has been established under the auspices of the British Society for Spondyloarthritis (BRITSpA) in collaboration with the National Axial Spondyloarthritis Society (NASS) to provide real-world data to evaluate the impact of delay in diagnosis (from symptom onset to diagnosis) on work participation and functional outcomes and the natural history and impact of newly-diagnosed axial Spondyloarthritis, including disease activity, pain, fatigue, functional and work outcomes, comorbidities, therapies in the United Kingdom (UK). The study is a prospective cohort, enrolling patients attending rheumatology clinics in the UK who are newly diagnosed with axial Spondyloarthritis and naïve to biologic therapy. The study will run for an initial 3 year period commencing January 2023. Financial support was provided as a Research Grant from Pfizer Limited, UCB and Novartis.