Solar container development guidance officially released

On August 15th, Treasury and the IRS released Notice 2025-42, which sets out the controlling standards for when construction is treated as having begun, narrows reliance on prior safe harbors, and details continuity, contracting, transferring, and low-output solar rules. On Friday, the US Department of the Treasury and the Internal Revenue Service (IRS) released comprehensive guidance (Notice 2025-42) regarding the beginning of construction of wind and solar energy projects for the purposes of qualifying for the §45Y production tax credit (PTC) and §48E investment. Treasury and the IRS today released guidance, Notice 2025-42 (the “ Notice ”), regarding what constitutes beginning of construction for solar and wind energy projects with respect to the production tax credit under Section 45Y of the Code (the “ PTC ”) and Section 48E of the Code (the “ ITC ”). On August 15, 2025, the IRS released Notice 2025-42 (the Notice) providing new beginning of construction (BOC) guidance for solar and wind projects claiming production and investment tax credits under sections 45Y and 48E of the Internal Revenue Code. The Notice is the product of an executive order. This notice provides guidance, consistent with Executive Order 14315 of July 7, 2025, Ending Market Distorting Subsidies for Unreliable, Foreign-Controlled Energy Sources, 90 F.R. 30821 (Executive Order 14315), regarding when construction of an applicable wind facility or applicable solar facility. On Friday, Treasury released Notice 2025-42, significantly modifying the longstanding beginning of construction (BOC) guidance that solar and wind taxpayers have relied on since 2013 to determine whether their projects meet the statutory tax credit termination dates. The guidance is effective. The Internal Revenue Service updated its guidance for what counts as beginning construction for solar and wind projects on August 15, 2025. The IRS issued the new guidance in response to Executive Order 14315 of July 7, 2025, wherein the Trump White House specifically ordered the Treasury.