India has approximately 43 Mtpa of blast furnace capacity due for reline before 2030. A reline decision made today locks in BF-BOF production — and its CCTS GEI compliance cost — for 15 to 20 years. Phase 1 CCTS targets (FY2025-26) require only 2-3% GEI reduction, costing most plants relatively little in CCC purchase or imposing modest operational change. But Phase 3 and Phase 4 targets — which BEE will set after 2027 calibrated against the 2035 NDC’s 47% intensity target and the industrial sector’s failure to reduce absolute emissions in 2025 — are likely to require GEI reductions of 5-10% per year, imposing materially larger CCC costs on every year of remaining BF-BOF campaign life. A 3 Mt BF-BOF plant relining today at an estimated cost of Rs 800-1,200 crore to secure 18 years of additional campaign life will face cumulative CCTS CCC costs of Rs 5,000-15,000 crore over that same campaign life — potentially exceeding the reline capex itself by a factor of 5-10. This article builds the complete upgrade-or-retire capital model for Indian blast furnace operators: reline cost benchmarks from Indian and global data, the CCTS cumulative carbon cost across a 15-20 year campaign at Phase 1 through Phase 4 target trajectories, the EAF conversion cost comparison, and the four decision scenarios that determine whether reline, retrofit, convert, or retire is the correct capital allocation for a given blast furnace in 2025-2027.