Legal Question in Family Law in California

Assets you own at the time of marriage do not become community property, but income from work does, as does income from assets (such as dividends, rental profits, or business profits) if it is mixed in accounts that have community property in them or used to buy joint assets. Also, the community can acquire an interest in the separate property assets from before the marriage in various ways. So a person who has any significant assets when they get married should at least get some legal coaching on how to handle those assets, and possibly a prenutual agreement.

Property owned before marriage is that person's separate property. If you give it to the other spouse as a gift, it can become the other spouse's separate property, or if you give it to the community, it can become community property. Subject to certain statutory requirements, this is called a transmutation.

In addition to separte property gaining a community property interest, as pointed out by Mr. McCormick, separate property can also become community property when it is commingled with community property and no longer traceable to a separate property source.