A premarital agreement is typically designed to preserve a party’s separate property and to explicitly spell out what property will be community property, if any, and what will remain or become separate property. It is a document that allows you to contract around Texas law. For example, under Texas law, interest earned on separate property is community property. However, you can stipulate otherwise in a prenuptial agreement. You also can specify that the money you earn during your marriage is your separate property rather than community property.