Key takeaways:
- A cheating clause (also called an infidelity clause) is a prenup or postnup term that changes money or property if one spouse is unfaithful.
- Nothing stops you from writing one, but whether a court will enforce it is uncertain and depends heavily on your state.
- In California, a court refused to enforce a $50,000 infidelity penalty because it conflicted with the state’s no-fault divorce policy (Diosdado v. Diosdado, 2002).
- No prenup can reduce a child’s right to support, and you would still need to prove the affair in court.
Last reviewed: October 22, 2026. This article is general information about US law, not legal advice. Laws change and every situation is different, so talk to a licensed attorney in your state about your own case.
You are planning a wedding and wondering whether you can write fidelity into your prenup: if one of you cheats, that person pays. It is a common question, and the honest answer is that you can usually put such a clause in writing, but you cannot count on a judge enforcing it. Here is what the law actually says and what to think about before you add one.
Contents
- What a cheating clause is
- What prenup law allows
- Do courts enforce them?
- The proof problem
- Alternatives worth discussing
- FAQ
What a cheating clause is
A cheating clause is a provision in a premarital agreement (signed before the wedding) or a postnuptial agreement (signed during the marriage) that is triggered by infidelity. Common versions include:
- A fixed payment to the faithful spouse, sometimes called liquidated damages
- Losing or reducing spousal support (alimony)
- Giving up a share of certain property, such as the family home
- Paying the other spouse’s attorney fees
Some couples see these clauses as a deterrent. Others want financial protection if trust is broken. Either way, the clause is only worth something if a court will enforce it.
What prenup law allows
Many states have adopted a version of the Uniform Premarital Agreement Act. North Carolina’s version is typical. It lets couples contract about property, its disposition “upon separation, marital dissolution, death, or the occurrence or nonoccurrence of any other event,” the modification or elimination of spousal support, and “any other matter, including their personal rights and obligations, not in violation of public policy or a statute imposing a criminal penalty” (N.C.G.S. 52B-4).
That last phrase is where cheating clauses run into trouble. A court may decide that a penalty for infidelity violates public policy, especially in a state where fault is not supposed to play a role in divorce.
Limits that apply to every prenup:
- A premarital agreement cannot adversely affect a child’s right to support (N.C.G.S. 52B-4(b), and the same rule appears in other states’ versions of the uniform act).
- Custody and parenting time are decided based on the child’s best interests at the time, not by a clause in your prenup.
- A prenup can be set aside if it was not signed voluntarily, or in many states if it was unconscionable and there was no fair financial disclosure.
Do courts enforce them?
There is no single national rule, and published court decisions on infidelity clauses are few. The clearest example comes from California.
Diosdado v. Diosdado (Cal. Ct. App. 2002): after the husband’s affair, the couple signed an agreement during the marriage. If either spouse later broke the duty of sexual fidelity and the marriage ended because of it, that spouse would move out, pay the related attorney fees and pay $50,000 in liquidated damages on top of the normal property and support orders. The court held the agreement unenforceable. It explained that a family law court in California “may not look to fault in dissolving the marriage, dividing property, or ordering support,” and called the penalty “in direct contravention of the public policy underlying no-fault divorce.”
That reasoning matters beyond California. Every state now offers no-fault divorce, and many states divide property without considering misconduct. In those states, a clause that brings fault back in through a private contract faces a serious public policy objection.
The picture is different in states where fault still counts by law. North Carolina, for example, already bars alimony for a dependent spouse who engaged in “illicit sexual behavior” during the marriage, and requires alimony when the supporting spouse did (N.C.G.S. 50-16.3A). A clause that lines up with rules like these may face less resistance than a flat cash penalty, but no published rule guarantees that.
Clauses also fail for ordinary drafting reasons: vague definitions of “cheating,” penalties that look punitive rather than compensatory, or general problems with how the prenup was signed.
Ask about severability. If you include a cheating clause, ask your attorney about a severability provision, so that a court striking the infidelity term does not put the rest of your prenup at risk.
The proof problem
Even an enforceable clause only works if the affair can be proven. That raises practical issues:
- Definition. Does the clause cover only sexual relationships, or also emotional affairs or online conduct? Undefined terms invite litigation.
- Evidence. Texts, financial records, witnesses or a licensed investigator’s report may be used. The standard of proof depends on your state and on how the clause is written.
- Privacy laws. Hacking accounts, installing spyware or secretly recording conversations can violate state or federal law, and illegally obtained evidence can be excluded or expose you to liability.
- Cost and stress. Litigating whether an affair happened adds time and legal fees, which may cost more than the clause is worth.
Alternatives worth discussing
If your real goal is protection rather than punishment, these options are often more predictable:
Often more predictable
- Clear separate property terms for assets you bring into the marriage
- Agreed spousal support terms that do not depend on fault
- Full financial disclosure, with a written record of what you exchanged
- Life insurance or estate planning terms to carry out the agreement
Less predictable
- Flat cash penalties per affair
- Vague behavior rules (social media, “inappropriate” contact)
- Any term about custody, parenting time or child support
- Penalties far out of proportion to any actual loss
Some couples also add non-binding commitments, such as agreeing to try counseling before filing for divorce. These can be meaningful promises to each other even if a court would not enforce them.
Some states have specific rules about independent legal advice, especially for spousal support waivers. Even where it is not required, separate advice for each partner makes it harder to argue later that someone did not understand the agreement. A family law attorney in your state can tell you how local courts have treated lifestyle clauses.
FAQ
Can you put a cheating clause in a prenup?
Usually yes, in the sense that you can write one. Whether a court enforces it depends on your state’s law and public policy, and courts in no-fault states may refuse, as a California court did in Diosdado v. Diosdado.
Are infidelity clauses enforceable in California?
A California appeals court refused to enforce a $50,000 infidelity penalty in 2002, holding that it conflicted with the public policy behind no-fault divorce. That makes cash penalties for cheating very unlikely to hold up there.
Can a cheating clause affect custody or child support?
No. A prenup cannot adversely affect a child’s right to support, and custody is decided based on the child’s best interests when the case is heard.
Is a postnup different from a prenup for a cheating clause?
The same public policy concerns apply. The California case that rejected an infidelity penalty involved an agreement signed during the marriage, after an affair had already happened.
Sources: Diosdado v. Diosdado (Cal. Ct. App. 2002); North Carolina Uniform Premarital Agreement Act, N.C.G.S. 52B; N.C.G.S. 50-16.3A.
