The U.S. Department of the Treasury is moving to pull back the curtain on one of the most opaque corners of the dark money world, an effort that could shine a light on the financial networks fueling decades of climate lawsuits against American energy companies.

In a recent announcement, Treasury said the Internal Revenue Service plans to revise its Form 990, the annual disclosure required of tax-exempt organizations, to provide clearer reporting on how nonprofits raise and spend money, particularly in areas like government grans and fiscal sponsorships.

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