§22–308.

    (a)    Creditable service on which the allowance of a member is based consists of:

        (1)    eligibility service, except as provided in subsection (b) of this section; and

        (2)    credit for unused sick leave as provided in § 20-206 of this article.

    (b)    (1)    Except as provided in paragraph (2) of this subsection, a member’s creditable service for a period of regular part-time employment equals the member’s actual employment during that period.

        (2)    Subject to paragraph (3) of this subsection, a member’s creditable service for a period of regular part-time employment equals the member’s eligibility service for that period if:

            (i)    the medical board determines that the member’s part-time employment is a result of a medically determined disability that prevents full-time work; and

            (ii)    the member then elects to make the contributions for full-time employment required by § 22-214 of this title.

        (3)    Except to the extent that a disability was aggravated after a member’s enrollment, paragraph (2) of this subsection does not apply to a disability incurred before a member’s enrollment.