Regulation Reduction Act of 2025This bill requires federal agencies to repeal certain existing rules prior to issuing a new rule.Specifically, the bill prohibits an agency from issuing a rule that imposes a cost or responsibility on a nongovernmental person or a state or local government unless it repeals three or more related rules.Additionally, an agency may not issue a major rule that imposes such a cost or responsibility unless (1) the agency has repealed three or more related rules, and (2) the cost of the new rule is less than or equal to the cost of the rules being repealed. A major rule is a rule that has resulted in or is likely to result in (1) an annual economic effect of at least $100 million; (2) a major increase in costs or prices for consumers, individual industries, government agencies, or geographic regions; or (3) significant adverse effects on competition, employment, investment, productivity, or innovation.Any such repealed rule must be published in the Federal Register.This bill does not apply to a rule or major rule that (1) relates to an internal agency policy or practice, (2) relates to procurement, or (3) is being revised to be less burdensome to decrease requirements imposed or compliance costs.Additionally, each federal agency must submit to Congress and the Office of Management and Budget a report that includes a review of each rule of the agency and that identifies whether each rule is costly, ineffective, duplicative, or outdated.