(a) A designation of beneficiary must be in writing, signed and witnessed, and received in the employing office (or in OPM, in the case of a retiree, or a compensationer, or a separated employee) before the death of the designator.

(b) A change or cancellation of beneficiary in a last will or testament, or in any other document not witnessed and filed as required by this section, will not have any force or effect.

(c) A witness to a designation of beneficiary is ineligible to receive payment as a beneficiary.

(d) Any person, firm, corporation, or legal entity may be named as beneficiary.

(e) A change of beneficiary may be made at any time and without the knowledge or consent of the previous beneficiary. This right cannot be waived or restricted.

(f) A designation of beneficiary is automatically cancelled whenever a separated employee is paid the unexpended balance.

(g)

(1) If the shares designated equal less than 100 percent, the undesignated portion will be paid according to the order of precedence provided in section 8424 of title 5, United States Code.

(2) If the shares designated exceed 100 percent, each designee's share will be in proportion to the share originally designated. Each share is computed by multiplying the percentage designated for that designee by a fraction whose numerator is 100 and whose denominator is the total number of percent designated.