The author examines the Supreme Court of India's 2026 decision in Tiger Global and its implications for the interaction between treaty entitlements and India's General Anti-Avoidance Rule. The judgment, it is argued, marks a decisive doctrinal shift from formal treaty compliance to a substance-over-form approach, reframing the 2016 Protocol's grandfathering clause from an inviolable guarantee to a rebuttable presumption subject to anti-avoidance scrutiny. By embedding GAAR principles into treaty interpretation, the Court subordinates legitimate expectations to domestic anti-abuse frameworks, ultimately conditioning treaty benefits on demonstrable commercial substance over mere formal compliance.