California has no statutory provision for a common law marriage.  That is no long you live together you are not married.  Community property laws apply only when there is a legally recognized marriage.  California does recognize common law marriages that occur in other states.  A couple living together and satisfiy the statutory requirements of the state for a common law marriage. would be considered a legal marriage in Californis.  Unles both parties agreed that there was a common law marriage, you would be required to prove that a common law marriage existed.