A prenuptial agreement, often shortened to “prenup,” is a written contract two people sign before getting married that spells out who gets what if the marriage ends in divorce or death. It replaces your state’s default rules on property, debts, and spousal support with terms the two of you choose. If the wedding never happens, the agreement never takes effect.
Why Couples Sign One
Every state already has rules for dividing assets when a marriage ends. Nine states use community property, which generally treats everything earned or acquired during the marriage as owned equally by both spouses. The other 41 states and the District of Columbia use equitable distribution, where a judge divides assets based on fairness rather than a strict 50/50 split.1Justia. Community Property vs. Equitable Distribution in Property Division A prenup overrides whichever system applies to you and substitutes your own agreement instead.
About half the states have adopted the Uniform Premarital Agreement Act, a model law that standardizes how these contracts are created, enforced, and challenged.2Uniform Law Commission. Premarital and Marital Agreements Act States that haven’t adopted it generally apply similar principles pulled from contract and family law.
What a Prenup Can Cover
The scope is broad. A prenup can address:
- Ownership, management, and control of any asset either person owns now or acquires later
- How property gets divided if the marriage ends in divorce or death
- Spousal support, including modification or waiver of alimony
- Who owns a life insurance policy and who receives the death benefit
- A requirement that one or both spouses create a will or trust carrying out the agreement
- Which state’s laws will govern the agreement if you move
The real work of most prenups is sorting assets into categories. Separate property is what someone owned before the wedding: a house, an investment account, a family business. Marital property is what gets acquired during the marriage, and the agreement can treat it as shared or as belonging to the earning spouse alone. Appreciation often needs its own clause. If you owned a home worth $300,000 before the wedding and it’s worth $500,000 at divorce, the agreement determines whether that $200,000 of growth is yours or partly your spouse’s.
Income earned during the marriage is another common target. Salaries, bonuses, and commissions are typically marital property under default rules, but a prenup can keep each spouse’s earnings separate. Inheritance rights are often spelled out too, so family wealth stays with the person it was passed to.
Debts
Prenups are as useful for debts as for assets. Pre-marital student loans or credit card balances can be assigned to the person who incurred them, and the agreement can set how debts taken on during the marriage will be split later. One important limit: the prenup only binds the two spouses. It does not bind third-party creditors. If both your names are on a mortgage or credit card, the lender can pursue either of you for the full balance regardless of what the agreement says. What the prenup can do is give you a right of reimbursement from your spouse if a creditor collects from you for their debt.
Spousal Support
Modifying or waiving alimony is one of the most powerful things a prenup can do, and also one of the most contested. Judges scrutinize these clauses more closely than property terms. An alimony waiver between two high-earning professionals with comparable assets gets less pushback than one where a spouse gave up a career to raise children and would face poverty without support. If circumstances have changed dramatically since the wedding, a court may refuse to enforce the waiver as unconscionable. Some couples sidestep the risk by writing in reasonable alimony terms instead of a flat waiver.
What a Prenup Cannot Do
Some topics are off-limits no matter what both parties agree to. A prenup cannot set child custody or limit child support. Support belongs to the child, not the parent, and a judge decides both based on the child’s circumstances at the time of separation, not on what two people wrote before the child existed.
Clauses that encourage divorce are also unenforceable. A promise of a financial bonus for filing would be struck down as contrary to public policy. Anything illegal is out too. If an agreement mixes valid and invalid terms, most courts will sever the bad provisions and enforce the rest, as long as the document includes a severability clause.
What Makes a Prenup Valid
A prenup is a contract, and it has to meet certain standards to hold up:
- It must be in writing and signed by both parties. Oral prenups are not enforceable.
- Signing must be voluntary. Pressure, threats, or coercion will get the agreement thrown out for duress.
- Each person must provide full and honest financial disclosure. Hiding a bank account or undervaluing a business can invalidate the entire agreement.
Independent Legal Counsel
Most courts don’t technically require each spouse to have a separate attorney, but the absence of independent legal advice is a red flag for a judge reviewing the agreement later. When one party had a lawyer drafting and explaining the terms while the other signed with no guidance, the agreement looks lopsided from the start. For alimony waivers in particular, some states will refuse to enforce the clause unless both parties were represented.
Timing
When the agreement gets presented matters as much as what it says. Handing your fiancé a prenup the night before the wedding creates an inference of pressure even without explicit threats. Some states have formalized this with waiting-period rules. Signing months before the wedding is far safer than signing days before, because both parties need real time to read it, consult a lawyer, negotiate changes, and decide.
How Prenup Protections Can Fall Apart Later
Even a well-drafted prenup can lose its force if the spouses don’t live within it. The most common breakdown is commingling: mixing separate and marital funds together. If your prenup designates a savings account as separate property but you start depositing joint paychecks into it, that account can lose its protected status. Routing separate funds through a joint account, even briefly, can convert them into marital property.
Keeping separate accounts for separate property, maintaining clear records, and avoiding casual transfers between accounts are all part of preserving what the agreement set up. A prenup creates the framework. The spouses have to actually use it.
Changing or Ending a Prenup
A prenup doesn’t automatically expire. Unless it says otherwise, it stays in effect for the entire marriage. Couples can include a sunset clause that ends some or all of the terms after a specific anniversary, the birth of a child, or a financial milestone like paying off pre-marital debt. Once a sunset trigger hits, the state’s default rules take over for whatever expired. A sunset clause won’t help, though, if divorce proceedings started before the trigger date.
Both spouses can also agree to amend or revoke the agreement after the wedding. The change has to be in writing and signed by both. One spouse cannot change the terms alone. An agreement signed or substantially rewritten after the marriage is called a postnuptial agreement. Postnups cover the same ground but face closer judicial scrutiny, because a married spouse is in a different bargaining position than someone who can still call off a wedding.
What It Costs
Attorney fees for drafting and negotiating a prenup generally run from $1,500 to $10,000 or more, depending on the complexity of your finances and the attorneys’ hourly rates, which commonly fall between $250 and $1,000 per hour. A simple agreement between two people with modest assets lands at the low end. A prenup involving business valuations, multiple properties, or trusts can push well past $10,000. Because each spouse should have independent counsel, you’re paying for two attorneys. Skipping the second one to save money is a false economy if it gives a judge reason to question the agreement’s fairness years later.