Is the SoFi rate simple or compounded? December 30, 2020 18:25 Updated Simple. The interest is calculated based on the principal amount of the loan. Related articles What is the timeframe for funding my Student Loan? How will funds be disbursed? Where can I enroll in the SoFi Member Rewards program? If I want to payoff my SoFi loan early, can I do so? Are there any prepayment penalties for paying off my loan early and/or making additional payments?