Traders assign a 95.5% implied probability against a corporate tax rate reduction before 2027 primarily because the One Big Beautiful Bill Act enacted in July 2025 already extended key TCJA business provisions—such as 100% bonus depreciation and interest limitations—without lowering the 21% statutory rate. With only months left in the 2026 legislative calendar, unified Republican control has prioritized tariffs, spending restraint, and other agenda items over another reconciliation package. Historical patterns show major rate changes require extended committee work, floor votes, and offsets that rarely compress into a short window. Realistic shifts could still arise from an unexpected fiscal crisis prompting emergency action, a post-election lame-duck session, or revised revenue estimates altering priorities, though these remain low-probability paths given current congressional timelines.