A written contract signed by spouses after they are already married that sets rules for money, property, debts, and sometimes how certain assets will be handled if the marriage ends or one spouse dies.

In plain terms, it is a way to put financial guardrails in place before a fight starts. A couple might use one to say a business stays separate, a house will be treated as community property or separate property, or one spouse will not be responsible for certain debts. In Texas, these agreements are generally governed by Texas Family Code Chapter 4 (2023), including rules that let spouses partition or exchange community property and convert property between community and separate status.

What matters in real life is whether the agreement was done carefully. A shaky postnup can fall apart if there was fraud, pressure, hiding assets, or sloppy drafting. That can turn a planned solution into a bigger divorce fight. Smart moves usually include full financial disclosure, clear language, and each spouse having a chance to get independent legal advice.

For a family law case, a postnuptial agreement can directly affect property division, spousal maintenance, and even who keeps a settlement or business interest. In Texas, it generally cannot waive child support in a way that binds a court, because the child's best interests come first. If there is already tension in the marriage, getting the terms reviewed before signing can save a lot of damage later.