An employee or Member who separates from service is entitled to an annuity—

Except as provided in paragraph (d) of this section, after attaining the minimum retirement age and completing 10 years of service; or

After becoming age 60 and completing 20 years of service; or

After becoming age 62 and completing 5 years of service.

Except as provided in paragraph (b)(2) or (c) of this section, an annuity payable under paragraph (a) of this section commences on the first day of the month following separation.

An annuity payable under paragraph (a) of this section commences on the day after separation, if that separation occurs upon the expiration of a term (or other period) for which the individual was appointed or elected.

An employee or Member entitled to an annuity under paragraph (a)(1) of this section may elect to postpone the commencing date of that annuity, provided the individual—

Has completed less than 30 years of service; and

Is not entitled to an immediate annuity under any other provision of this subpart. An immediate annuity means an annuity that will begin within 31 days of separation.

A postponed commencing date may not precede the later of—

The first day of the month after the date of separation of the employee or Member; or

The 31st day after the date of filing the election of a commencing date.

A postponed commencing date must be no later than the second day before the employee's 62nd birthday.

The election of a commencing date may be filed not more than 90 days before the commencing date elected by the employee or Member, and must be filed in a form prescribed by the Office of Personnel Management (OPM).

A written election that is not in the prescribed form, but which designates a specific commencing date, and otherwise conforms to the time limits in paragraphs (c)(2) through (c)(4) of this section, will be accepted as an informal election subject to ratification in the prescribed form.

The election of a commencing date becomes irrevocable on the date OPM authorizes the first annuity payment.

If an employee or Member separates from service after attaining the minimum retirement age and completing 10 years of service, but is reemployed before filing an application for retirement based on that separation, the individual may not elect an annuity commencing date that precedes separation from the reemployment service.

In the case of an employee or Member who separates from service after attaining the minimum retirement age and completing 10 years of service, and is reemployed after filing an application for retirement based on that separation, that individual may not elect an annuity commencing date that precedes separation from the reemployment service if he or she is reemployed prior to a postponed commencing date elected under paragraph (c) of this section.