A prenuptial agreement is a legal contract signed by two people before they marry that determines how their assets, debts, and finances will be handled if the marriage ends in divorce, separation, or death. Most people have heard of them. Far fewer understand what they actually cover, what they cannot cover, and what makes one enforceable. The short version: a prenup is a financial agreement, not a statement of distrust, and it gives both partners clarity about where they stand before the marriage begins rather than leaving those questions to a court years later.
What a prenup actually covers
The core purpose of a prenuptial agreement is to define how property will be characterized and divided if the marriage ends. Without a prenup, state law determines what counts as marital property subject to division at divorce. With a prenup, the couple sets their own rules within the limits the law allows.
Prenups typically address which assets each partner brings into the marriage and how they will be treated, whether those assets remain separate property or become marital property over time, how property acquired during the marriage will be divided, how debts each partner brings in will be handled, and whether either spouse will receive spousal support (alimony) after a divorce and in what amount. They can also address what happens to a business one partner owns, how an inheritance received during the marriage will be treated, and how financial responsibilities will be divided during the marriage itself.
One area prenups are used for that surprises people: protecting children from a prior relationship. A parent entering a second marriage may want to ensure that assets they plan to leave to their children from the first marriage remain clearly separate and are not subject to division or claims by a future spouse. A prenup can define those assets explicitly, creating a clear boundary that a will or trust alone does not always provide.
What a prenup cannot cover
Prenups have real limits, and provisions that cross those limits will not be enforced even if both parties signed them willingly.
Child custody and child support are the most significant exclusions. Courts will not enforce prenuptial provisions that predetermine custody arrangements or waive a child's right to support. Those decisions are made at the time of divorce based on the child's best interests, not on an agreement made years earlier before the child existed. Any prenup provision attempting to address child-related matters is effectively unenforceable.
Provisions that incentivize divorce are also unenforceable. A clause that promises one partner a large payout specifically triggered by filing for divorce, as opposed to a general property division framework, can be struck down as contrary to public policy. Courts have also refused to enforce provisions that attempt to regulate personal behavior during the marriage, such as clauses about housework, weight, frequency of visits to in-laws, or other lifestyle matters. Those provisions are not just unenforceable; they can create an impression of overreach that courts sometimes use to scrutinize the entire agreement more closely.
Anything fraudulent or based on incomplete financial disclosure is also problematic. Both partners must fully disclose their assets and debts before signing. A prenup that was negotiated while one partner concealed significant assets, or that was signed without each partner having a genuine opportunity to review it, is vulnerable to being thrown out entirely.
What makes a prenup enforceable
Enforceability is where many prenups fail. The agreement that seemed solid when signed can unravel years later if the execution did not meet the legal requirements. The requirements vary by state, but several principles apply broadly.
The agreement must be in writing and signed by both parties. Verbal prenups do not exist in any enforceable sense. Both parties must have had full and fair disclosure of each other's financial situation before signing, meaning assets, debts, income, and any other material financial information. Both parties must have signed voluntarily, without duress or coercion. Handing someone a prenup the night before the wedding and presenting it as a take-it-or-leave-it condition is the kind of circumstance courts examine carefully for coercion.
Timing matters. The closer to the wedding date the prenup is signed, the more scrutiny it receives. Most attorneys recommend completing and signing the prenup at least 30 days before the wedding, and ideally much earlier. This gives both parties adequate time to review it, negotiate terms, and consult independent counsel without the pressure of an imminent ceremony.
Independent legal representation for each party is not legally required in most states, but it is one of the strongest protections against a later challenge. When both parties had their own attorneys, courts are much more reluctant to find that the agreement was signed under duress or without adequate understanding of the terms. If one party chooses not to retain an attorney after being given the opportunity, the prenup typically includes a written acknowledgment of that choice.
How prenups differ from postnuptial agreements
A postnuptial agreement covers the same general subject matter as a prenup but is signed after the marriage has already taken place. Postnups are used when couples did not get around to a prenup before the wedding, when circumstances change significantly during the marriage (a business launch, an inheritance, a major shift in one partner's income), or when a couple going through a difficult period wants to clarify financial expectations as part of working through the relationship.
Postnups face somewhat more legal scrutiny than prenups in some states because courts are more alert to the possibility of duress within an ongoing marriage. The enforceability standards are similar, but the context is different. A prenup negotiated before the marriage begins is evaluated as a prospective planning agreement between people who are not yet legally bound to each other. A postnup negotiated during a marriage is evaluated in a context where one party may have more leverage than the other. The full coverage of postnups is in a separate article, but the distinction is worth knowing when deciding whether the timing of a prenup matters for your situation.
State law variations worth knowing
Most states have adopted some version of the Uniform Premarital Agreement Act (UPAA), which standardizes the basic requirements for prenup validity. But adoption has not been uniform, and states have modified the model act in meaningful ways.
California adopted the UPAA but added a requirement that each party have at least seven days to review the agreement before signing, and that any unrepresented party receive a specific written explanation of the agreement's terms. New York has not adopted the UPAA and evaluates prenups under general contract principles, with courts historically willing to enforce them if they meet basic contract requirements. Texas courts enforce prenups but apply close scrutiny to voluntariness and disclosure. Florida adopted the UPAA and generally enforces prenups that meet its requirements, including the absence of fraud, duress, or inadequate disclosure. Illinois adopted a modified version of the UPAA and requires both voluntariness and fair and reasonable disclosure.
The state where you live when you divorce, not necessarily where you signed the prenup, often determines which state's law governs enforcement. A choice-of-law provision in the prenup can specify which state's law applies, though courts will not always honor that provision if enforcement would violate the forum state's public policy.
A Real Scenario
A software engineer in Seattle is getting married. He owns a startup that has grown significantly in the two years since he founded it, and his future spouse works in education with a modest salary and no significant assets. Both agree that a prenup makes sense given the financial asymmetry, but neither wants the conversation to feel like a statement about the marriage's odds. They work with a couples-friendly service that guides both partners through the process together, each reviewing and negotiating terms with their own counsel, and sign the agreement six weeks before the wedding. The key provisions: his startup equity and any proceeds from a future sale remain his separate property, any real estate they purchase together during the marriage is marital property split equally, and neither waives spousal support entirely but they agree on a capped formula tied to the length of the marriage.
Getting a prenup without the adversarial dynamic
One of the reasons couples avoid prenups is the assumption that the process requires dueling attorneys and a confrontational negotiation. That is the high-conflict version, and it is not the only version. Online platforms designed specifically for prenups have made the process more accessible and less adversarial, guiding both partners through the same questions together and producing a document that reflects their shared decisions rather than one side's demands.
HelloPrenup is one of the better-known platforms of this type, designed to let couples build their prenup collaboratively online before having attorneys review and finalize it. For couples who want a fair, clearly drafted prenup without the cost and friction of starting from scratch with separate attorneys, it is worth looking at as a starting point.
Frequently Asked Questions
Does getting a prenup mean you expect the marriage to fail?
This is the most common objection and the least legally relevant one. A prenup is a financial planning document, the same category as a will or a business partnership agreement. Nobody signs a will because they expect to die soon, and nobody forms a business partnership agreement because they expect the business to fail. Both documents exist because clarity about financial arrangements before the fact is better than ambiguity resolved under stress. Surveys consistently show that couples who discuss finances openly before marriage, including the prenup conversation, report higher satisfaction with their financial relationship during the marriage.
Can a prenup be thrown out by a judge?
Yes. Courts can invalidate a prenup entirely or strike specific provisions for several reasons: inadequate financial disclosure by either party, evidence of duress or coercion at signing, unconscionable terms that were grossly unfair at the time of execution, failure to meet the technical execution requirements of state law, or provisions that violate public policy such as child support waivers. A prenup that was signed under time pressure without independent counsel is more vulnerable to challenge than one negotiated carefully over weeks with both parties represented. The most common reason prenups fail in court is inadequate disclosure, not unfair terms.
Do both people need separate lawyers for a prenup?
Legally required in only a handful of states, but strongly advisable for both parties. An attorney who represents one partner cannot represent the other, since their interests may conflict. A partner who signed without reviewing the agreement with independent counsel has a stronger argument later that they did not fully understand what they agreed to. Some couples use online platforms to draft the prenup collaboratively and then each has a separate attorney review it before signing, which balances cost with adequate protection. The investment in independent review is small relative to the stakes if the agreement is ever challenged.
Can you get a prenup after you're already engaged?
Yes. Being engaged does not preclude a prenup; it just means you are working against a deadline. The closer to the wedding date the agreement is signed, the more likely a court is to look carefully at whether both parties had adequate time and were not pressured by the imminence of the ceremony. Most attorneys and prenup platforms recommend starting the process as early as possible once engagement is decided, and completing it no later than 30 days before the wedding. Starting after the engagement is announced is fine. Starting the week before the wedding is not.
What happens if we move to a different state after signing a prenup?
The prenup generally travels with you, but the enforcing state's law applies unless the agreement includes a valid choice-of-law clause specifying otherwise. If you signed a prenup in a state with permissive enforcement rules and later move to a state with stricter requirements, the stricter state's courts may evaluate the agreement under their own standards when applying it at divorce. Community property states like California, Texas, and Arizona have their own rules about marital property that interact with prenup provisions in specific ways. Reviewing an existing prenup with an attorney in the new state after a significant move is a reasonable precaution, particularly if the move is to a community property state from an equitable distribution state or vice versa.