The Biden Administration has taken numerous actions to address student loan debt. These actions have ranged in scope (both in terms of the borrower populations affected and associated modification costs), their rationales, and the avenues through which they were taken (e.g., formal rulemaking procedures, issuance of guidance). One effect of these actions is they have resulted in changes in the costs of outstanding federal student loans, measured in terms of the value in today's dollars of a direct loan or loan guarantee's future cash flows. Opponents of these actions emphasize the extent of cost increases, while supporters contend that these actions help address borrower difficulty in managing and repaying student loan debt. The Department of Education's (ED's) Office of Federal Student Aid (FSA) annually reviews outstanding federal student loans to ensure that, as required by the Federal Credit Reform Act of 1990 (FCRA), enough budget authority is obligated to cover cost increases resulting from action that fits the category of a modification. A modification is government action--whether resulting from new legislation or an exercise of existing agency discretion--that changes direct loans' or loan guarantees' costs. FSA reports modifications and their costs in its annual reports. Annual reports published for FY2021-FY2024 identify numerous modifications (including one that resulted from a change in statute) for which FSA calculated a change in the costs of outstanding student loans. Most of these resulted in modification costs. The remainder resulted in downward modification costs. ED recognized downward modification costs after the Supreme Court ruled in June 2023 that the COVID-19-related, broad-based student loan debt relief policy exceeded the Secretary of Education's statutory authority. ED also reported downward modification costs due to transitioning student loan debt collection services from private collection agencies to Business Process Operations vendors. ED estimated that modification costs in the federal student loan programs totaled about $77 billion in FY2021 and $450 billion in FY2022. In FY2023, ED recognized a total $207 billion downward modification cost. During FY2021-FY2024, ED's single largest modification cost resulted from the announcement of the COVID-19-related, broad-based debt relief policy, totaling $353 billion. In the same period, the single largest downward modification cost, a $333 billion savings, resulted from the Supreme Court's vacatur of that broad-based debt relief policy.