India’s blast furnace fleet has an average age exceeding 20 years. Every blast furnace reaching the end of its campaign faces a three-way decision: reline at Rs 800–1,200 crore and run for another 12–15 years of BF-BOF production, retire without replacement, or retool toward an EAF-based steelmaking route. At current CBAM costs, coking coal prices, and CCTS GEI trajectories, the financial arithmetic of this decision has shifted materially since 2022. This article maps the full cost comparison.