Legal Question in Real Estate Law in Florida

401K has special Federal ERISA rules. IRA does not.

First, not sure what you mean by a "separate property State". Florida is an "Equitable Distribution" state. Typically assets that are accumulated during a marriage are considered "Marital Assets" with a few exceptions and/or with express waiver by the spouse. This would include 401(k) investments and growth during the time frame of the marriage.

Since your 401(k) is an asset that a spouse would typically have a claim in, the express waiver of beneficiary will be required in order to protect the company from lawsuits for improper distribution upon your death. It reads like you may have additional questions about what is and IS NOT part of the marital estate. If so, you should schedule a consultation with a family law attorney and pay them a relatively small fee to provide you advice.

Good luck.