(a) Subject to subsections (b) through (d) of this section, the Board of Trustees shall adopt regulations that specify the period of employment in a year that is equal to 1 year of service credit.

(b) The Board of Trustees may not allow more than 1 year of service credit for a calendar year.

(c) Except as provided in subsection (d) of this section or § 22-304(c)(2) of this subtitle, a member is entitled to receive:

(1) 1 year of service credit for:

(i) employment for the normal working time in a year for the member’s position; or

(ii) regular part-time employment for a calendar year; and

(2) 1 month of service credit for employment for a month or a part of a month if a member contribution is made in the month.

(d) (1) Except as otherwise provided in this subsection, a member of the Employees’ Retirement System who is an elected or appointed official is entitled to receive 1 year of service credit for each 12-month period during which the member holds the office.

(2) Except for an official of a participating governmental unit, an appointed official who is appointed on or after July 1, 1979, is not entitled to receive service credit if the normal working time for the position is less than 130 days per year.

(3) An elected or appointed official who purchases service credit under § 22-307 of this subtitle, is entitled to receive 1 year of service credit for a part of a year of employment if the part of the year is at least equal to the number of days of the regular session of the General Assembly for the year for which the service credit is requested.