What if a debt is not included in the Prenuptial Agreement?

That will not affect the validity of the agreement. The disclosure of debts serves primarily to inform each fiancé about the other’s liabilities before marriage. Regardless of disclosure you will not become liable for your fiancé’s debts after you are married unless you affirmatively adopt them by signing a debt instrument. So long as there is no community property being created during the marriage your property will not be used to satisfy your spouse’s debts. A prenup can ensure that no community property is created during the marriage.