What You Can and Cannot Include in a Prenup

What Can and Cannot Go in a Prenup: The Short Answer

Prenups handle financial matters. They can divide property, assign debts, set alimony terms, and address business interests. They cannot decide child custody, determine child support, or contain illegal or purely lifestyle-based terms. Enforceability depends on your state's law, honest financial disclosure from both partners, and truly voluntary signing.

Here's a quick overview:

What You Can Include in a Prenuptial Agreement

The list of what a prenup can cover is long, and it centers on money, property, and financial expectations. Under the Uniform Premarital Agreement Act (UPAA), which about 29 states plus D.C. have adopted in some form, couples can address the rights each person has in property owned before the marriage or acquired afterward, how that property will be divided, and whether spousal support will be paid.

Separate and Marital Property

Every asset owned before the marriage can be designated as separate property: real estate, bank accounts, vehicles, investment portfolios, collectibles. The typical approach is to create disclosure schedules, often called Schedule A (one partner's assets and debts) and Schedule B (the other's), attached to the agreement. These schedules aren't just paperwork. They become the proof that both partners knew exactly what they were agreeing to, which matters if the agreement is ever challenged.

You can also define what happens to property acquired during the marriage. In community property states, the default rule treats most assets earned during marriage as jointly owned 50/50. In equitable distribution states, a judge divides assets based on fairness rather than a strict formula. A prenup overrides both defaults, but only when the document is specific and clear about how each category of property should be treated.

Debt Allocation

Prenups can keep pre-marital debt out of the marital estate and specify which partner is responsible for debts incurred after the wedding. This is especially relevant when one partner carries significant student loans, credit card balances, or small-business debt. Without a prenup, creditors may be able to go after marital property even when only one spouse is the debtor.

Business Interests

For many couples, a business is the entire reason for a prenup. Without one, a business that appreciates in value during the marriage can be deemed partly marital property, and the other spouse may be entitled to a share. A prenup can specify that the business remains separate property and outline how any appreciation during the marriage will be handled.

Spousal Support (Alimony)

Couples can waive alimony entirely, cap it at a fixed monthly amount, set a lump-sum buyout, or build a formula tied to the length of the marriage. Some agreements increase the payout at milestones like five or ten years. It's worth knowing that alimony payments under divorce agreements finalized after December 31, 2018, are not tax-deductible for the payer and not taxable income for the recipient, a change from prior law that affects how couples structure these terms.

Some states place limits on alimony waivers. Under the UPAA, a court can step in and override a waiver if enforcing it would leave one spouse eligible for public assistance at the time of divorce.

Additional Provisions

Beyond the major categories, a prenup can address:

• Retirement benefits: How 401(k)s, pensions, and IRAs are treated
• Inheritance handling: Keeping inherited assets separate
• Life insurance: Beneficiary designations and coverage requirements
• Tax filing: Income, deductions, and filing status during the marriage
• Household finances: Management of joint bank accounts, bill payments, credit card spending, and savings contributions
• Dispute resolution: Requiring mediation or arbitration before litigation
• Choice-of-law clause: Specifying which state's laws govern the agreement if the couple moves
• Sunset clause: Setting an expiration date or review trigger for the agreement

What You Cannot Include in a Prenup

Courts draw firm lines around several categories, and including prohibited terms can weaken or void parts of the agreement.

Child Custody and Child Support

No state allows parents to predetermine child custody, parenting time, or child support amounts in a prenup. Courts always decide these issues based on the best interests of the child at the time the question arises, using current circumstances and state guidelines rather than what two people agreed to years earlier. Child support belongs to the child, not the parents, so it can't be bargained away in advance.

Illegal Terms

Every state prohibits illegal provisions. Including one can put the entire document at risk, depending on the jurisdiction.

Lifestyle Clauses

Clauses about household chores, weight requirements, frequency of visits to in-laws, social media behavior, or similar personal matters are typically unenforceable. Judges focus on financial and legal matters, not personal conduct rules. While couples sometimes include these clauses informally, relying on them in court is a losing strategy.

Infidelity Penalties

Provisions that impose financial penalties for cheating are treated inconsistently across states. In many jurisdictions, these clauses are either unenforceable or considered risky enough that attorneys advise against including them.

Terms That Incentivize Divorce

Provisions that financially reward one spouse for ending the marriage, such as a large lump-sum payment triggered by filing for divorce, are generally frowned upon and may be struck down as contrary to public policy.

Unconscionable Alimony Waivers

While you can waive or limit alimony in many states, a court can override the waiver if it's so lopsided that it shocks the conscience or would leave one partner destitute. The fairness of an alimony provision is evaluated not just at the time of signing but also at the time of enforcement.

Community Property vs. Equitable Distribution: Why State Rules Matter

Your state's default property-division system determines what happens if you divorce without a prenup, and it shapes what your prenup needs to address.

Nine states follow community property rules: Arizona, California, Idaho, Louisiana, Nevada, New Mexico, Texas, Washington, and Wisconsin. In these states, most assets and debts acquired during the marriage are jointly owned 50/50 by default. The remaining 41 states (plus D.C.) use equitable distribution, where a judge divides marital property based on fairness, considering factors like each spouse's income, the length of the marriage, and contributions to the household. The IRS outlines community property rules in Publication 555, which also affects how couples file taxes during the marriage.

A prenup overrides the default regime, but only as far as the document is clear. Vague language about "my stuff stays mine" won't cut it. The agreement needs to specifically identify asset categories and spell out the rules.

If you move to a different state after the wedding, a choice-of-law clause in the prenup helps determine which state's rules apply. Courts generally honor the clause as long as the selected state has a genuine connection to the couple and the chosen law doesn't violate the new state's public policy.

What Makes a Prenup Enforceable in 2026

An agreement that covers the right topics but was signed the wrong way can still be thrown out. Courts evaluate both procedural fairness (how the agreement was made) and substantive fairness (whether the terms are reasonable).

Procedural Requirements

• Written and signed by both parties. Oral promises about property division carry no legal weight.
• Voluntary signing. Neither partner can be pressured, threatened, or rushed into signing. Presenting a prenup the night before the wedding, for example, raises serious duress questions.
• Full financial disclosure. Each person must provide a clear picture of what they own and owe. Hidden assets or omitted debts can be enough for a judge to void the agreement entirely. A party can waive further disclosure in writing, but only after receiving a fair and reasonable baseline.
• Time to review. Both partners need adequate time to read, understand, and negotiate the terms.

Independent Counsel

Most states don't technically require each partner to have their own attorney, but the absence of separate counsel is always a red flag for judges. When one lawyer drafts the agreement and only one side gets legal advice, the other partner has a much stronger argument that they didn't fully understand what they signed. Independent counsel for each partner is highly recommended for an enforceable prenup.

With Neptune, each party works with an independent attorney they choose from Neptune's network of lawyers. Having both partners independently represented helps address the procedural fairness concerns that courts examine when reviewing a prenup.

Substantive Fairness

Even a properly executed prenup can be challenged if the terms are grossly one-sided. Courts ask whether the agreement was so unfair at the time of signing that it "shocks the conscience." In some states, this analysis also looks at fairness at the time of enforcement, not just at execution.

Federal Considerations

Two federal issues catch couples off guard:

• ERISA and retirement accounts. Federal law governs spousal rights in employer-sponsored retirement plans (401(k)s, pensions). A prenup signed before marriage cannot waive a spouse's rights under ERISA because those rights don't exist until the marriage occurs. A separate waiver is typically needed after the wedding.
• Post-2018 alimony tax treatment. For divorce agreements finalized after December 31, 2018, alimony is no longer deductible for the payer or taxable for the recipient. This changes the math on how couples structure support provisions.

As Michael C. Cotugno, Esq., Managing Partner of Neptune Legal, puts it: "A premarital agreement doesn't have to be a wedge between partners or a necessary evil that protects assets at the expense of trust and intimacy." When approached as a shared planning exercise, the conversation itself can strengthen a couple's financial alignment before the wedding.