OBJECTIVES: To explore healthcare, sickness absence (SA), and disability pension (DP) cost trajectories among people with multiple sclerosis (PwMS) following diagnosis, accounting for socioeconomic characteristics and comorbidities. METHODS: All PwMS in Sweden, 25-60 years old at MS diagnosis, according to the National Patient Register, were included. Microdata were linked from several nationwide registers. Four cohorts, based on diagnosis year (2006-2009) were followed prospectively, for 5 years, regarding 1) direct costs: healthcare and out-of-pocket expenditure, and prescribed drugs, and 2) indirect costs: SA and DP. Average per patient costs were calculated, in 2017 Swedish Krona (SEK). A group-based trajectory Poisson model was used, mapping cost progression and assessing heterogeneity based on socioeconomic characteristics (age, gender, education, type of living area, geographic region, country of birth, marital status), and comorbidities at diagnosis year. RESULTS: Five cost trajectories were identified among the 3272 PwMS. One, where 32.2% of PwMS belonged, had high direct and indirect costs, first increasing and then decreasing. This was in line with the average direct costs in the overall study population, increasing the 1st year, and then declining 3 years after (e.g., for the 2009 cohort, from SEK 87,796 to 97,801, and then to 80,394). Another trajectory had low direct and indirect costs, first decreasing and then increasing, possibly explained by the decrease in SA over time and increase in DP, indicating a shift from short-term to long-term social security benefits. A 3^rd trajectory, where only 2.4% of PwMS belonged, had high direct and indirect costs, which decreased substantially after 4 years. Finally, the last two trajectories had either high direct or indirect costs. Socioeconomic consequences and comorbidities differed significantly across trajectory groups. CONCLUSIONS: There is heterogeneity across sub-groups of newly diagnosed PwMS; their socioeconomic and health outcomes differ significantly, leading to different cost trajectories over time.