Prenups and Postnups: What They Can and Can't Do (and Who Needs One Most)

Key Points:

The stigma is gone. A 2026 Harris Poll conducted for Bloomberg found 53 percent of engaged or married Americans under 45 have signed a prenup, and women now initiate nearly half of them.

All 50 states enforce prenuptial agreements, but only ones done right: voluntary, with full financial disclosure, fundamentally fair, and ideally with independent counsel on both sides.

Prenups have hard limits. No agreement can decide child custody or child support in advance, and federal financial aid rules ignore prenups entirely.

A postnuptial agreement is the same tool signed after the wedding, and it can serve couples working to stabilize a marriage rather than end one.

The people who need these agreements most aren't the ultra-wealthy. They're people remarrying after divorce, with children, obligations, and assets from a prior life to protect, exactly when second and later marriages carry the highest divorce risk.

In my practice, marital agreements used to arrive with an apology. Clients would explain that they weren't planning for failure, and ask whether wanting was a reason not to get married. That conversation has changed completely, and the numbers show why. A generation ago, roughly 3 percent of married Americans had a prenup; by 2022 it was 15 percent, and as of this year, a majority of engaged or married Americans under 45, 53 percent, report having signed one. Couples marry later, arrive with their own assets and debts, and, notably for readers of this site, an enormous number of them are marrying for the second time. And the truth is, you wouldn't start a business without a partner agreement, so why would you get married without a prenup?

What Is a Prenuptial Agreement, Really?

A prenuptial agreement is a contract between two people who plan to marry, defining how financial matters will be handled if the marriage ends in divorce or death. Rather than leaving those questions to your state's default rules and a judge's discretion, you and your future spouse decide for yourselves, in advance, while you like each other.

A well-drafted prenup can address:

Property division. Defining what counts as separate property (what each of you brings in, inheritances, gifts) versus marital property, and how marital property will be divided.
Spousal support. Setting, limiting, or in many states waiving alimony, one of the most fiercely litigated issues in divorce.
Debt. Clarifying who is responsible for which debts, protecting one spouse from the other's student loans, business liabilities, or medical debt.
Business interests. For business owners, keeping the company, its appreciation, and its operations out of a future divorce. As I tell my business-owner clients: your partners and employees have a stake in your marriage whether they know it or not.
Inheritance and estate coordination. Protecting assets intended for children from a prior marriage, which for remarrying parents is often the entire point.

Beyond the legal terms, there's a benefit clients rarely expect: the process forces a complete, honest financial conversation before the wedding. Full disclosure of assets, debts, income, and expectations is legally required for enforceability, and couples routinely tell me the disclosure conversation was the most valuable financial talk they'd ever had. An agreement most couples hope never to use still delivers that value on day one.

What a Prenup Cannot Do

This is where I correct the most misconceptions, so let me be direct about the limits:

It cannot decide child custody or child support. Courts determine custody based on a child's best interests and support based on circumstances at the time of divorce, and the right to support belongs to the child, not the parents. Any provision pre-deciding these issues is unenforceable, full stop.
It cannot bind the federal government. Planning for college? Financial aid rules ignore prenuptial agreements entirely: a stepparent's income must be reported on the FAFSA regardless of any agreement absolving them of college costs. If education funding matters in your family, coordinate your agreement with the realities we cover in our guide to college expenses in divorce.
It cannot be shockingly unfair or signed under pressure. Courts refuse to enforce agreements that are unconscionable or products of fraud, duress, or coercion. An agreement that leaves one spouse destitute invites exactly the litigation it was supposed to prevent.
It cannot include illegal terms or lifestyle provisions with legal teeth. Clauses about chores, weight, or frequency of visits from in-laws make for colorful drafting requests, but courts won't enforce them.

What Makes a Marital Agreement Enforceable

All 50 states recognize and enforce prenuptial agreements, with many following versions of the Uniform Premarital Agreement Act, but enforcement is earned at the drafting table. Across jurisdictions, courts look for the same fundamentals:

Voluntariness. Both parties signed freely, without coercion. Timing is the classic red flag: an agreement presented days before the wedding invites a duress challenge, while one negotiated months in advance is far more defensible. Start early. The prenup conversation belongs near the engagement, not near the rehearsal dinner.
Full and fair financial disclosure. Each party must honestly disclose assets, debts, and income. Hidden accounts discovered later are the fastest way to watch an agreement collapse.
Fundamental fairness. The agreement can favor one party, but it cannot be unconscionable, and some states test fairness both at signing and at enforcement.
Independent counsel. Not strictly required everywhere, but each party having their own attorney is the single best insurance policy for enforceability, because it defeats later claims that one spouse didn't understand what they signed.

One caution from my corner of the profession about the do-it-yourself route: online prenup platforms have made these agreements affordable, which is genuinely good, but DIY agreements carry real enforceability risks: missing state-specific requirements, including unenforceable custody provisions, and inviting duress claims where no lawyers were involved. If you use a platform for drafting, at minimum have independent attorneys review before signing. An unenforceable prenup is worse than none at all, because you'll have relied on it.

The Postnup: Same Tool, Different Timing

A postnuptial agreement covers the same ground as a prenup but is signed after the wedding. Couples reach for postnups in several situations I see regularly: the prenup conversation that never happened before the wedding, a major change in circumstances (an inheritance, a business launch, one spouse leaving the workforce to raise children), and, most delicately, a marriage under strain.

That last one deserves attention on a site like this. For some couples working through a rough chapter, a postnup functions as an alternative to divorce: it settles the financial anxieties that are poisoning the relationship, so the couple can work on the marriage itself without the money fight underneath everything. A spouse who stayed home for a decade can get security in writing; a spouse who received an inheritance can protect it; and both can stop negotiating through resentment. It doesn't save every marriage, but I've watched it lower the temperature in more than a few.

Two honest cautions. First, some states scrutinize postnups more strictly than prenups, because married spouses owe each other fiduciary duties that engaged couples don't. Second, a postnup negotiated when one spouse has already consulted a divorce attorney sits in delicate territory. Both are reasons this particular agreement belongs in experienced hands, and if your marriage is struggling, pairing the legal work with a marriage coach addresses the relationship while the agreement addresses the money.

Remarrying After Divorce? This Is Your Agreement

Here is the audience these agreements serve best, and it's likely you. If you're remarrying after a divorce, consider what you're bringing to this marriage that you didn't bring to your first: children with inheritance expectations, support obligations or rights under a prior decree, retirement assets you've rebuilt once already, perhaps a business, and hard-earned knowledge of exactly how expensive an unplanned divorce can be.

The statistics say the caution is warranted, not cynical. Remarried adults over 50 divorce at roughly 2.5 times the rate of those in first marriages, and second marriages generally end at higher rates than first ones. A prenup for a second marriage does protective work a first-marriage prenup rarely has to: it can guarantee that assets intended for your children actually reach them, coordinate with your estate plan so your new spouse and your kids aren't set up for a future conflict, and ensure that obligations from your first divorce, support, insurance, college contributions, are accounted for rather than colliding with new promises. For readers rebuilding after a gray divorce, where the runway to recover from another financial setback is short, I consider this conversation less optional than any other I have with clients.

Already Have a Prenup and Facing Divorce?

If you're heading into a divorce with an agreement already in place, two opposite mistakes are common: assuming the prenup is ironclad, and assuming it's hopeless. Neither is automatic. Enforceability turns on the factors above: how it was signed, what was disclosed, whether it was fair, and whether you had counsel. An agreement signed under wedding-week pressure without disclosure or independent advice may be vulnerable; one negotiated properly will very likely hold, and courts enforce them regularly. Either way, have a family law attorney in your state review the agreement early, because it will shape every other decision in your case, including whether the cooperative alternatives to litigation make sense for you.

The Conversation Is the Hard Part

The law of marital agreements is manageable. The conversation is what stops people, because raising a prenup can feel like planning for failure with the person you love most. Reframe it the way this generation of couples has: an agreement is a plan made together, while you're partners, instead of a fight conducted later, through lawyers, when you're not. Couples who can talk honestly about money before marriage are practicing the exact skill that protects marriages, and couples who can't may be learning something important too. If the conversation itself feels impossible, that's work a coach can help with before any lawyer drafts a word.

This article is for general informational purposes only and is not legal advice. Marital agreement requirements vary significantly by state, and enforceability depends on specific facts. Consult a family law attorney in your jurisdiction about your situation.

Frequently Asked Questions

Are prenups enforceable in all 50 states? Yes, every state recognizes and enforces prenuptial agreements, though requirements vary. Enforcement generally depends on voluntary signing, full financial disclosure, fundamental fairness, and, as a practical matter, independent attorneys for both parties. State-specific rules make local counsel essential.

Can a prenup decide child custody or child support? No. Courts decide custody based on the child's best interests and support based on circumstances at the time of divorce, and no agreement can waive a child's right to support in advance. Any custody or child support provision in a prenup is unenforceable.

What is the difference between a prenup and a postnup? Timing. A prenuptial agreement is signed before marriage; a postnuptial agreement covers the same financial ground but is signed after the wedding. Postnups are often used when circumstances change during marriage or when couples want to resolve financial tensions while working on the relationship, though some states scrutinize them more closely.

Should I get a prenup for a second marriage? For most people remarrying after divorce, yes, or at least a serious consultation. Second marriages carry higher divorce risk, and remarrying spouses typically have children, prior support obligations, and rebuilt assets to protect. A prenup coordinated with your estate plan protects both your new spouse and your children from a future conflict.

What makes a prenup invalid? The common attacks are duress (signed under pressure, especially right before the wedding), fraud or hidden assets during disclosure, unconscionability (shockingly unfair terms), and lack of understanding, which is why independent counsel for both parties matters. Illegal provisions, and any terms about child custody or support, fail regardless.