In a significant development for the U.S. solar industry, a federal court has overturned IRS Notice 2025-42—effectively restoring the long-standing 5% safe harbor for establishing the “beginning of construction” under Sections 45Y and 48E.
For developers managing projects larger than 1.5 MW, this ruling creates a short-term strategic window to re-evaluate how projects qualify for federal tax credits before the July 4, 2026 deadline.
