If you decided to look through the Texas Family Code to learn about prenuptial agreements, you would not find them. Instead, Texas statutes refer to them as premarital and marital property agreements. To be valid, this type of agreement must be a written document signed by both you and your future spouse.
A premarital agreement does not go into effect until you are married. If you want to change anything in it after you are married, you must agree in writing about any amendments or revocations, and both of you must sign it. The agreement is not valid if a judge determines that your marriage is void.
There are other factors that would make the document unenforceable. For example, there should be no major undisclosed financial obligations or property. If you include a written waiver that says you do not need to have everything disclosed, or if you could reasonably have known that your future spouse had the property or obligation, then this is not a factor in the document's enforceability. However, without these two, and without the disclosure, the premarital agreement could be considered unconscionable and invalid. The court has to provide the ruling to this effect.
Most people probably think of issues regarding the division of marital property when they think about premarital agreements. It could also involve spousal support, though, as you and your future spouse could decide that one or both of you will waive the right to receive alimony if you get a divorce. However, you cannot waive or otherwise affect the amount of child support awarded.
Because each premarital agreement is a unique legal document, this general information should not be interpreted as legal advice, or replace the counsel of an attorney.