; and (II) may be adjusted by the Secretary from time to time by increasing or decreasing such percentages as the Secretary considers necessary, based on the performance of mortgages insured under this subsection and market conditions. (ii) Prohibition of monthly premiums A mortgage insured under this subsection shall not be subject to a monthly insurance premium, including a premium under subsection (c)(2)(B). (4) Eligible mortgagors The mortgagor for a mortgage insured under this subsection shall, at the time the mortgage is executed— (A) be a first-time homebuyer; (B) have completed a program of housing counseling provided through a housing counseling agency approved by the Secretary; (C) as attested by the mortgagor— (i) be employed as a first responder; (ii) have been— (I) employed as a first responder for not less than 4 of the 5 years preceding the date on which the mortgagor submitted an application to insure the mortgage under this section; or (II) released from employment as a first responder due to an occupation-connected disability resulting from such duty or employment; (iii) be in good standing as a first responder and not on probation or under investigation for conduct that, if determined to have occurred, is grounds for termination of employment; (iv) in good faith intend to continue as a first responder for not less than 1 year following the date of closing on the mortgage; and (v) have previously never been the mortgagor under a mortgage insured under this subsection; (D) meet such requirements as the Secretary shall establish to ensure that insurance of the mortgage represents an acceptable risk to the Mutual Mortgage Insurance Fund