A member is entitled to: eligibility service as provided in §§ 24-303 through 24-306 of this subtitle; and creditable service as provided in § 24-307 of this subtitle.

Subject to subsections (b) and (c) 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. The Board of Trustees may not allow more than 1 year of service credit for a calendar year. A member is entitled to receive 1 month of service credit for employment for a month or a part of a month if a member contribution is made in that month.

Eligibility service for a member consists of service credit: for employment as a member; regained under § 24-304 of this subtitle by a member who redeposits accumulated contributions previously withdrawn; transferred from a retirement or pension system under Title 37 of this article; for military service as provided in Title 38 of this article; or purchased under this subtitle.

A member who previously terminated membership and withdrew accumulated contributions from either the State Police Retirement System, the Employees’ Retirement System, or the Teachers’ Retirement System may receive service credit for the period of employment during the previous membership if the member redeposits in a single payment the withdrawn accumulated contributions plus regular interest to the date of redeposit. If a member receives service credit under this section, the member may not retire within 3 years from the date the member enters or reenters the State Police Retirement System.

Except as provided in subsection (b) of this section, a member may not purchase service credit under this title if the member is separated from employment. A member who is separated from employment may purchase service credit under this title for a leave of absence approved by the Board of Trustees under regulations that apply to all members, if the member purchases the service credit within 60 days after the expiration of the leave of absence. For good cause shown, the Executive Director, in the Executive Director’s sole discretion, may extend the time period to purchase service credit under paragraph (1) of this subsection if: the purchased service credit would allow the member to meet the eligibility service requirements to apply for an ordinary disability retirement under § 29–105(a) of this article; and the member completes the purchase of the service credit before the earlier of: 4 years after the expiration of the leave of absence; or the date membership ends. The Board of Trustees shall adopt regulations to carry out this subsection.

A member may purchase service credit as provided in subsection (b) of this section: for a period of employment when the member was on an employer-approved leave of absence not exceeding 2 years that has qualified for purchase under regulations adopted by the Board of Trustees; or when membership was mandatory but for which member contributions were not made. A member who purchases service credit under this section shall: complete a claim for the service credit and file it with the Board of Trustees on the form that the Board of Trustees provides; and pay to the Board of Trustees in a single payment the member contributions the member would have made for the period of employment for which service credit is being purchased plus regular interest to the date of payment. A member may pay for service credit purchased under this section at any time before retirement.

A member may purchase service credit as provided in this section for periods of employment described in subsection (c) of this section for which the member is not otherwise entitled to service credit. A member who purchases service credit under this section shall: complete a claim for the service credit and file it with the Board of Trustees on the form that the Board of Trustees provides; and pay to the Board of Trustees an amount equal to the annuity reserve and pension reserve required to fund the additional allowance. The member shall pay for service credit purchased under this section in a single payment at retirement. A member may purchase service credit for a period of employment not exceeding 10 years for: federal service; or out-of-state service with a political subdivision.

Creditable service on which the allowance of a member is based consists of: eligibility service; and credit for unused sick leave as provided in § 20-206 of this article.