; and (B) which may be subordinated to any other lien securing project obligations. (c) Base interest rate The base interest rate on a direct loan under this Act shall be not less than the yield on Treasury obligations of a similar maturity to the maturity of the direct loan on the date of execution of the loan agreement. (d) Risk assessment Before entering into an agreement for assistance under this Act, the Chief Executive Officer, in consultation with the Director of the Office of Management and Budget and each rating agency providing a preliminary rating opinion letter under this section, shall determine an appropriate Federal credit subsidy amount for each direct loan and loan guarantee, taking into account that preliminary rating opinion letter, as well as any comparable market rates available for such a loan or loan guarantee, should any exist. (e) Credit fee (1) In general With respect to each agreement for assistance under this Act, the Chief Executive Officer shall charge a credit fee to the recipient of that assistance to pay for, over time, all or a portion of the Federal credit subsidy determined under subsection (d), with the remainder paid by the account established for IFA. (2) Direct loans In the case of a direct loan, the credit fee described in paragraph (1) shall be in addition to the base interest rate established under subsection (c). (f) Maturity date The final maturity date of a direct loan or loan guaranteed by IFA under this Act shall be not later than 35 years after the date of substantial completion of the eligible infrastructure project, as determined by the Chief Executive Officer. (g) Preliminary rating opinion letter (1) In general The Chief Executive Officer shall require each applicant for assistance under this Act to provide a preliminary rating opinion letter from at least 1 rating agency, indicating that the senior obligations of the eligible infrastructure project, which may be the Federal credit instrument, have the potential to achieve an investment-grade rating. (2) Rural