I have litigated several set aside cases involving undisclosed assets. One of my favorite cases involved a wife whose husband was hiding over $50,000 in an undisclosed bank account. After the account was discovered, the Court awarded wife 100% of the asset and the husband was ordered to pay $10,000 of the wife's attorney's fees in addition to her receiving the $50,000 from the bank account. It is very important to disclose all of the assets and debts and failure to do so can be very costly.
California law requires the parties to disclosure all of the assets and debts, community, quasi-community, or separate property to the other party during the process of divorce. If either party fails to properly disclose an asset, then they could be subject to penalties that include losing 100% of the value of the undisclosed asset and paying the other side's attorney's fee.