A public economic framework was used to explore lifetime government costs and benefits in relation to the Pediatric Immunization Program (PIP) in Belgium based on cases and deaths averted. To estimate changes in net government revenue, we developed a decision-analytic model that quantifies lifetime tax revenues and transfers based on changes in morbidity and mortality arising from Belgium’s Pediatric Immunization Program (PIP). The model considered differences in incidence rates with vaccines included in Belgium’s PIP: compared with the pre-vaccine era. Changes in deaths and comorbid conditions attributed to PIP on the Belgium 2020 birth cohort were used to estimate gross lifetime earnings changes, tax revenue gains attributed to averted morbidity and mortality avoidance, disability transfer cost savings, and averted special education costs associated with each vaccine. Vaccinating a single birth cohort according to the PIP gives rise to fiscal gains of €56 million in averted tax revenue loss, €8 million disability savings, and €6 million special education cost-savings. Based on the costs of implementing the PIP, we estimate the fiscal benefit–cost ratio (fBCR) of €2.2 investment return for the government from every €1 invested excluding longevity costs. Reducing vaccine-preventable conditions generates tax revenue for the government, providing fiscal justification for sustained immunization investments.