Except as provided in subsection (b) of this section, in the year of retirement, a member of the Employees’ Pension System may purchase credit for eligibility service of up to 10 years for periods of employment described in paragraph (3) of this subsection for which the member is not otherwise entitled to service credit. To purchase service credit under this subsection, a member must: 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. A member may only purchase service credit under this subsection for employment with: the State; a political subdivision in the State; an out–of–state school as a teacher; the federal government; an out–of–state political subdivision; a public or nonpublic school as a teacher; or a postsecondary school as a teacher. This subsection does not apply to an employee of a participating governmental unit or a former participating governmental unit that has withdrawn. In the year of retirement, a member of the Employees’ Pension System may purchase credit for eligibility service for periods of employment with the State for which the member is not otherwise entitled to service credit in a State system. A member who purchases service credit under this subsection may not purchase: more than a total of 10 years of service credit in the Employees’ Pension System; service credit for any period of employment during which the member participated in the optional retirement program; or more than a total of 5 years of service credit in the Employees’ Pension System for employment as a postsecondary school teacher. To purchase service credit under this subsection, a member must: 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 one–half of the annuity reserve and one–half of the pension reserve required to fund the additional allowance. A member of the Employees’ Pension System may purchase credit for eligibility service for previous service in a position described in § 23-204(a) of this title. To purchase the service credit, the member must pay in a single payment, the contributions, with interest, that the Board of Trustees considers appropriate. A member of the Employees’ Pension System who is employed by a member of the State Senate or House of Delegates for at least 130 days per year as a legislative employee before becoming a member is considered to have been a permanent part–time legislative employee. A member described in paragraph (1) of this subsection may purchase credit for eligibility service for that period of legislative employment by paying to the Board of Trustees: for a period of employment on or before December 31, 1979, the sum of: the amount that the member would have been required to contribute for that period of employment; and 5% regular interest on the member’s contributions, compounded annually; and for a period of employment on or after January 1, 1980, the sum of: one–half of the amount that the member would have been required to contribute for that period of employment; one–half of the amount that the State would have been required to contribute for the member for that period of employment; and 5% regular interest on the member’s and State’s contributions, compounded annually.