SIAM Journal on Financial Mathematics, Volume 12, Issue 2, Page SC-16-SC-30, January 2021.
American student loans are fixed-rate debt contracts that give borrowers the option to repay their balances in full by a fixed maturity, or to enroll in income-based schemes, whereby payments are proportional to their income above subsistence, and any balance remaining after several years of payments is forgiven but taxed as income. For a small loan, the cost-minimizing repayment strategy dictates maximum payments until full repayment, forgoing both income-based schemes and forgiveness. For a large loan, income-based repayment is optimal, either immediately or after a period of maximum payments. The critical balance depends on the loan rate, the tax rate, and the forgiveness horizon. Overall, income-based repayment significantly benefits large but not small borrowers.

中文翻译：

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简短交流：美国学生贷款：还款和估值

SIAM 金融数学杂志，第 12 卷，第 2 期，第 SC-16-SC-30 页，2021 年 1 月。
美国学生贷款是固定利率债务合同，让借款人可以选择在固定期限内全额偿还余额，或加入基于收入的计划，其中付款与他们的生活收入成正比，并且在数次之后剩余的任何余额多年的付款被免除，但作为收入征税。对于小额贷款，成本最小化的还款策略规定在全额还款之前最大还款额，放弃基于收入的计划和宽恕。对于大笔贷款，基于收入的还款是最佳的，无论是立即还款还是在最大还款期之后。临界余额取决于贷款利率、税率和宽恕期限。总体而言，基于收入的还款显着使大借款人受益，但并非小借款人。