The Treasury Department and the IRS have issued Notice 2026-15, providing interim guidance on how taxpayers should determine whether certain energy projects receive “material assistance” from a prohibited foreign entity and therefore become ineligible for key federal energy tax credits. 

According to a report from the IRS, the One Big Beautiful Bill Act (OBBBA) added new restrictions to the clean electricity production and investment credits under Sections 45Y and 48E, as well as the advanced manufacturing production credit under Section 45X. Under the new law, facilities and components may lose eligibility if they receive material assistance from a prohibited foreign entity, commonly referred to as a PFE. 

The notice states that Treasury and the IRS “intend to propose regulations with respect to the definition of a PFE and the calculation of the material assistance cost ratio that taxpayers must use to determine whether there was material assistance from a PFE.” In the meantime, the guidance outlines interim safe harbors authorized by the OBBB and provides example calculations to help taxpayers apply those rules. 

Taxpayers may rely on the notice for certain projects, including Section 45Y or 48E facilities that begin construction after Dec. 31, 2025, and Section 45X components sold in taxable years beginning after July 4, 2025, until forthcoming safe harbor tables are published. Treasury and the IRS have also requested comments within 45 days on definitional and anti-circumvention issues as they prepare formal regulations.