5 CFR 843.208 - Notification of current and/or former spouse before payment of unexpended balance to a separated employee.
(b) Proof of notification will consist of a signed and witnessed statement by the current and/or former spouse on a form provided by OPM acknowledging that he or she has been informed of the former employee's application for the unexpended balance and the consequences of the refund on the current or former spouse's possible annuity entitlement. This statement must be presented to the employing agency or OPM when filing the application for the unexpended balance.
(1) Affidavits signed by two individuals who witnessed the employee's attempt to personally notify the current or former spouse. The witnesses must attest that they were in the presence of the employee and the current or former spouse and that the employee's purpose should have been clear to the current or former spouse; or
(2) The current mailing address of the current or former spouse. OPM will attempt to notify (by certified mail - return receipt requested) the current or former spouse at the address provided by the employee. The unexpended balance will not be paid until OPM receives the signed return receipt.