I have actually dealt with this multiple times. For any qualified retirement plan, pursuant to the Retirement Equity Act of 1984, if the participant is married and has not elected the spouse as the sole primary beneficiary, spousal consent must be obtained as witnessed by a notary or an authorized plan representative. The QJSA rules are irrelevant. The spouse can disclaim all or a portion of his or her benefits, but the disclaimer has to be valid under his/her state law (we refer the spouse to obtain legal counsel). Whatever portion is disclaimed is treated as if there is no beneficiary designation and the terms of the plan document kick in. As someone has previously stated, the anti-assignment clause of ERISA would not permit the spouse to name the person who would get the assets.