Background: Generalized myasthenia gravis (gMG) is a potentially life threatening chronic autoimmune disease that can impair patients’ ability to work effectively and increase reliance on public support benefits. A public economic framework was used to explore how treatment influences patients’ and caregivers’ economic activity, including tax revenues and public support in Canada. Methods: Natural history of gMG was simulated using a multi-state Markov cohort model. Health states were based on MG Activities of Daily Living (MG-ADL) total score in patients with AChR-Ab+ refractory gMG. Treatment, costs, and economic outcomes of patients taking efgartigimod were compared with alternative therapeutic options. Canadian public support benefits were based on official government sources. Results: Improved MG-ADL states predict higher workforce participation, lower rates of disability and less caregiving needs, resulting in higher tax revenues and less public support costs. Compared to alternative therapeutic options, efgartigimod is estimated to yield lifetime fiscal gains of $458,755 that exceed the incremental cost of $291,073, suggesting the Canadian government receives $1.6 for every $1.0 spent on efgartigimod for the treatment of gMG. Conclusions: Compared with alternative options, efgartigimod generated a positive fiscal return for the Canadian governments with additional savings from disease management, public benefits, and averted tax revenue losses.