Responsible Borrowing Act of 2021 This bill authorizes institutions of higher education (IHEs) to prorate or limit the amount of a Federal Direct Loan that an enrolled student may borrow for an academic year. The bill specifies the factors that an IHE may use to limit these loans. These factors include the average starting salary for typical occupations pursued by graduates of the program, the enrollment status of the student (i.e., full- or part-time enrollment), the credential level of the program (e.g., degree or certificate), and the year of the program for which the student is seeking the loan. Upon request of a student whose loan has been prorated or limited, an IHE may increase the amount of the loan within otherwise applicable limits if the student demonstrates special circumstances or exceptional need.