I've always said, "A little bit of legal knowledge is a dangerous thing." Nevertheless, I just read something that stated some legal concepts that every Texan should know.
Section 3.001 of the Texas Family Code defines a spouse's separate property as the property owned or claimed by the spouse before marriage; the property acquired by the spouse during marriage by gift, devise, or descent; and the recovery for personal injuries sustained by the spouse during marriage, except any recovery for loss of earning capacity during marriage.
There can also be issues of tracing to separate property. But I won't go into all of that here.
Section 3.002 of the Texas Family Code defines community property as the property, other than separate property, acquired by either spouse during marriage. So, the presumption regarding the property of a married person is that it is all community property. Again, that's the presumption, not the proven fact.
Texas law provides that income from separate property during the marriage is community property. There is a major exception to this rule, but this is the rule.
Finally, a premarital agreement can and very often does make what would otherwise be community property instead be separate property. A post-nuptial agreement can do that, too. That is, by agreement – if done properly – spouses can agree their way around the basic community property rules of Texas.
That is a little bit of legal knowledge. Be careful with it.