<p>Income loss after breast cancer is an important area of research, but long-term impacts and heterogeneous effects are understudied. Here, we measure the effect of breast cancer on personal and household equivalized income of females in Denmark from 2000-2018 using Danish register data. We perform a cohort study and match on age, income, employment, comorbidities, healthcare utilization, and other socioeconomic and demographic variables at cohort entry, to investigate impacts across subpopulations over 10 years. We also perform an event study difference-in-difference analysis over the same period. Our study finds personal income loss averaging €7138 over 10 years in the non-retired population. The working population, students, and those in worse health suffer disproportionate loss. Household income losses are smaller and recover within 10 years. Overall, the Danish economic protections are effective in mitigating long-term economic impact of breast cancer, though there is room for improvement in protection of the most vulnerable.</p>