The TSP Fiduciary Security Act of 2026 aims to enhance the responsibilities of fiduciaries managing the Thrift Savings Fund, a retirement savings plan for federal employees and members of the uniformed services. The primary goal is to ensure that fiduciaries prioritize the best interests of beneficiaries while safeguarding national security. Key provisions of the Act require fiduciaries to avoid investments that could jeopardize U.S. national security, including how they exercise voting rights associated with those investments.