Forecasting health expenditures have policy implications of better resource planning and prioritizing equitable access if one could predict such future health financing needs. We use a top-down, past growth accounting model as demonstrated by Rocha et al. 2019 in Brazil, as the availability for administrative microdata in Indonesia were relatively limited. We estimate an annual increase of 2.71% in the share of health expenditure relative to GDP in Indonesia, reaching 4.12% of GDP in 2035, keeping pace with GDP growth. This growth is primarily driven by economic expansion and residual factors, underscoring the role of macroeconomic conditions in shaping health financing trends. Indonesia’s expanding social health insurance schemes are anticipated to increase the public sector’s share of health spending, raising critical questions about long-term financial sustainability. Our results show considerable robustness from our sensitivity analyses, and comparisons of other forecast studies.