; or (II) any fixed 12-month plan year; or (ii) meets eligibility requirements of the plan that otherwise permit participation prior to the date described in clause (i). (B) Hours of service For the purposes of this paragraph, the determination of an employee’s hours of service shall be made in a manner consistent with section 202(a)(3)(C), except that the number of such hours may be estimated by the employer. (3) Employment positions A qualified flexible workplace arrangement plan may specify which employment position or positions are offered participation in a particular workflex option described in paragraph (1). (4) Clarification A qualified flexible workplace arrangement plan shall not be required to offer an employee more than one workflex option without regard to whether another employee is offered more than one workflex option. (b) Conditions A qualified flexible workplace arrangement plan shall offer a workflex option under subsection (a) to employees pursuant to the following: (1) Voluntary participation (A) In general Except as provided in subparagraph (B)(i), an employee’s participation in any workflex option offered under a qualified flexible workplace arrangement plan shall be voluntary and the acceptance of a workflex option may not be a condition of employment. (B) Agreement or understanding A workflex option shall be carried out pursuant to— (i) applicable provisions of one or more agreements described in section 801(a)(1)(B); or (ii) in the case of an employee who is not subject to an agreement referred to in clause (i), a written agreement— (I) setting forth the employee’s work schedule; (II) including a description of the workflex option in which the employee is participating; (III) executed before the employee begins to participate in such workflex option