A prenuptial agreement is something you and your partner create prior to your marriage. It typically covers financial aspects of your relationship and how you will handle them if you get a divorce in the future, but these agreements may contain other details as well.
According to the Texas Constitution and Statutes, to be legally binding, your prenuptial agreement must be signed by both parties and in writing. It cannot be an oral agreement.
You can include almost anything you want in an agreement as long as it is not illegal or criminal. You cannot include anything related to child support in it. If you do, the court will void that portion of the document.
Your agreement goes into effect when you legally marry, and you cannot change it after that without agreement by both of you. In addition, any changes must be in writing.
You both must sign the agreement of your own free will without coercion and with complete knowledge of what is in the document. Also, there must be full disclosure by both people of all financial information.
The court has the final say as to the validity of a premarital agreement. A judge will review it and determine if part or all of it is invalid. A judge can void certain sections or the whole agreement. It depends on the legality of the creation and contents of the document as to what the judge will decide. If declared legal, you and your partner must abide by the directions provided in the agreement.