All civilian service as a Federal employee, as defined in 5 U.S.C. 2105(a), is creditable for purposes of this part. Civilian service performed in employment that does not meet the definition of Federal employee set forth in 5 U.S.C. 2105(a) is creditable for purposes of this part only if specifically authorized by statute as creditable for retention purposes.

As authorized by 5 U.S.C. 3502(a)(A), all active duty in a uniformed service, as defined in 5 U.S.C. 2101(3), is creditable for purposes of this part, except as provided in paragraphs (b)(2) and (b)(3) of this section.

As authorized by 5 U.S.C. 3502(a)(B), a retired member of a uniformed service who is covered by § 351.501(d) is entitled to credit under this part only for:

The length of time in active service in the Armed Forces during a war, or in a campaign or expedition for which a campaign or expedition badge has been authorized; or

The total length of time in active service in the Armed Forces if the employee is considered a preference eligible under 5 U.S.C. 2108 and 5 U.S.C. 3501(a), as implemented in § 351.501(d).

An employee may not receive dual service credit for purposes of this part for service performed on active duty in the Armed Forces that was performed during concurrent civilian employment as a Federal employee, as defined in 5 U.S.C. 2105(a).

The agency is responsible for establishing both the service computation date, and the adjusted service computation date, applicable to each employee competing for retention under this part. If applicable, the agency is also responsible for adjusting the service computation date and the adjusted service computation date to withhold retention service credit for noncreditable service.

The service computation date includes all actual creditable service under paragraph (a) and paragraph (b) of this section.

The adjusted service computation date includes all actual creditable service under paragraph (a) and paragraph (b) of this section, and additional retention service credit for performance authorized by § 351.504 (d) and (e).

The service computation date is computed on the following basis:

The effective date of appointment as a Federal employee under 5 U.S.C. 2105(a) when the employee has no previous creditable service under paragraph (a) or (b) of this section; or if applicable,

The date calculated by subtracting the employee's total previous creditable service under paragraph (a) or (b) of this section from the most recent effective date of appointment as a Federal employee under 5 U.S.C. 2105(a).

The adjusted service computation date is calculated by subtracting from the date in paragraph (d)(1) or (d)(2) of this section the additional service credit for retention authorized by § 351.504(d) and (e).