; or (2) make a contribution of 8 percent of their annual payroll to the Medicare Trust Fund under title XXII of the Social Security Act. (c) Employee choice An employee may opt out of a qualifying employer sponsored plan as satisfied by subsection (b)(1) in order to enroll in Medicare for America. The employer shall be exempt from the contribution specified in subsection (b)(2). The Secretary of Health and Human Services shall have authority to set standards for determining whether employers or insurers are undertaking any actions to affect the risk pool within Medicare for America by inducing individuals to decline coverage under a qualifying employer sponsored plan and instead to enroll in Medicare for America. An employer violating such standards shall be treated as not meeting the requirements of subsection (a). (d) Special rules (1) Annual payroll For purposes of this paragraph, the term annual payroll means, with respect to any employer for any calendar year, the aggregate wages paid by the employer during such calendar year. (2) Aggregation rules Related employers and predecessors shall be treated as a single employer for purposes of this subsection. (3) Reduction for part-time employees In the case of a part-time employee, the employer contribution requirements of paragraph (1) shall be treated as satisfied if the employer contribution with respect to such employee is not less than the part-time employment ratio of the contribution required under paragraph (1). (4) Rules related to part-time employment For purposes of this subsection— (A) Part-time employee The term part-time employee means, with respect to any month, an employee who works on average fewer than 30 hours per week. (B) Part-time employment ratio The term part-time employment ratio means, with respect to a part-time employee of an employer in a month, a fraction— (i) the numerator of which is the number of hours in the employee's normal work week, and (ii) the denominator of which is 30 hours. (C) Special rules Under rules prescribed by the