The "Renewing Efficiency in Government by Budgeting Act of 2025," or REG Budgeting Act of 2025, mandates that the Director of the Office of Management and Budget (OMB) establish annual limits on additional unfunded regulatory costs . These limits apply collectively to all agencies and individually to each agency for the upcoming fiscal year. Agencies are required to submit proposed limits and justifications to the Director, who may also require reductions in cumulative unfunded regulatory costs to offset new ones. A significant provision dictates that any limit allowing a net increase in additional unfunded regulatory costs cannot be implemented without congressional approval through a joint resolution. Until such approval is granted, a default limit of no net increase in costs will be enforced. The Director must report these established limits to appropriate congressional committees and publish them on a designated website. If an individual rule would cause an agency to exceed its established limit, it cannot take effect without specific congressional approval. Agencies must notify the Director if a proposed rule might exceed limits, providing justification and detailing any considered alternatives. The Director then determines whether the limit would be exceeded and whether to concur with the agency's decision to proceed. Exceptions to reporting prohibitions exist for rules related to emergencies, criminal law enforcement, national security, or international trade agreements. The bill enhances transparency by requiring agencies to include a statement in final rule notices indicating whether the rule exceeds cost limits, by how much, and providing justification. It also establishes an Associate Administrator for Regulatory Budgeting within the Office of Information and Regulatory Affairs of OMB to oversee the implementation of these requirements and issue guidelines. Furthermore, the bill allows for judicial review for individuals aggrieved by agency actions related to these regulatory cost limits. Finally, the Director is required to submit an annual report to Congress detailing the administration of these limits, including any instances where limits were exceeded and the justification for doing so. The bill defines key terms such as "additional unfunded regulatory cost" and "unfunded regulatory cost," and explicitly exempts rules concerning monetary policy from its provisions.