No, but you can enter into a post-nuptial agreement.
By using a post-nuptial agreement, you and your spouse can choose to opt out of California's community property laws and agree to treat your assets as separate property.
You should consult with an attorney to take care of this for you. Our firm is located in Long Beach.
DISCLAIMER: The information in and this communication are not intended to create an attorney-client relationship between you and me or my law firm. The information in this communication is intended for general informational purposes only and should be used only as a starting point for addressing your legal issues. It is not a substitute for an in-person or telephone consultation with an attorney licensed to practice in your jurisdiction about your specific legal issue, and you should not rely upon the information in this communication. You understand that this communication is not confidential and is not subject to attorney-client privilege.
As noted in the previous answer, you cannot (because it's no longer PRE-nuptial) but you CAN make a "post-marital" agreement.
Making a binding post-marital agreement is more complex than making a binding pre-marital agreement, requires more complicated financial disclosure in the document, and there may be some things which you can do in a pre-marital agreement which you simply can't do at all in a post-marital agreement.
Sign up to receive a 10-part series of useful information and legal advice about the divorce process.