Can a divorce order divide my retirement benefits?
Yes. The court order must expressly direct the Office of Personnel Management to pay a portion of your benefits to the former spouse. The ex-spouse’s share must be stated as a fixed amount, a percentage or fraction of the annuity, or in terms of some other formula whose value is readily apparent from the face of the order and information in the government’s files.

Note that these payments cannot begin until you begin receiving retirement benefits. Money that is held by an employing agency or OPM and that may be payable at some future date is not available for payment under court orders directed at annuities.