A marriage contract covers the financial terms of your marriage and its possible end: which assets stay separate, which are shared, how debts are allocated, whether spousal support is paid or waived, and what each spouse inherits if the other dies. It replaces the property-division rules your state would otherwise apply. What it cannot do is decide child custody or support, waive certain federal benefits, change how the IRS treats your taxes, or regulate personal behavior between spouses. Signed before the wedding, the document is a prenuptial agreement; signed after, a postnuptial.
What the Contract Can Cover
Every state has default rules for dividing property when a marriage ends. Nine community property states presume most assets acquired during the marriage belong equally to both spouses. The other 41 states and the District of Columbia use equitable distribution, where a judge divides marital property based on what seems fair. A marriage contract overrides whichever system applies to you.
Roughly 28 states and the District of Columbia have adopted a version of the Uniform Premarital Agreement Act, which sets a consistent framework for what these contracts can address. Under the UPAA, couples can contract about the rights and obligations of each party in property “whenever and wherever acquired or located,” the management and control of that property, and how it is divided upon separation, divorce, or death.1American Academy of Matrimonial Lawyers. The Uniform Premarital Agreement Act and Its Variations Throughout the States In practice, that authority translates into a handful of standard categories.
Separate and Marital Property
The contract draws a line between what each person owned before the marriage and what the couple accumulates afterward. A business you started before the wedding, an inheritance, or a brokerage account funded with pre-marriage savings can be classified as separate property that stays with the original owner if the marriage ends. Income earned during the marriage and assets purchased with that income are typically marital property, and the contract specifies how they get divided.
This classification does more work than most people expect. Without a contract, many states treat the appreciation on your pre-marriage assets as marital property when marital effort or funds contributed to that growth. A contract can prevent that result by defining the rules up front.
Debt Allocation
The agreement can state that a spouse who brought student loans, credit card balances, or a car loan into the marriage stays solely responsible for those obligations. Mortgage payments on a shared home can be structured so that equity tracks each person’s actual contributions. Without a written agreement, some states treat pre-marriage debt repaid with marital funds as creating a reimbursement claim that complicates divorce proceedings.
Spousal Support
Couples can agree on a specific alimony amount, a formula tied to the length of the marriage, or a complete waiver. These limits are generally enforceable as long as they don’t leave one spouse destitute. Courts in most states retain authority to override a support waiver that would cause extreme financial hardship, and the UPAA specifically allows courts to refuse enforcement when an agreement was unconscionable at signing.1American Academy of Matrimonial Lawyers. The Uniform Premarital Agreement Act and Its Variations Throughout the States Some states add their own rules on top. In California, any clause limiting spousal support is unenforceable unless the waiving spouse was represented by an attorney.
Day-to-Day Household Finances
Many contracts go beyond divorce planning and set out how money will be managed during the marriage. They might require a joint account for shared household expenses while each spouse maintains a separate account for personal spending. This kind of provision rarely sees a courtroom, but it heads off the low-grade friction that builds when two people with different money habits merge their finances without a shared framework.
Sunset Clauses
A sunset clause causes the entire agreement to expire after a set period or milestone. Couples commonly choose five, ten, or twenty years from the date of marriage, or tie expiration to an event like the birth of a child or the purchase of a first home. Once the clause triggers, the contract no longer applies, and the couple reverts to the state’s default rules. The language must specify an exact date or clearly defined event; vague terms like “after several years” can render the clause unenforceable.
Inheritance and Elective-Share Waivers
Most states give a surviving spouse the right to claim a minimum share of the deceased spouse’s estate regardless of what the will says. This is called an elective share. A marriage contract can include a waiver of that right, meaning the surviving spouse agrees not to override the deceased spouse’s estate plan. These waivers are especially common in second marriages where each spouse wants to preserve assets for children from a prior relationship. The waiver must meet the same disclosure and voluntariness standards as any other provision in the contract.
What the Contract Cannot Cover
Child Custody and Support
Courts decide custody, visitation, and child support at the time of separation using the best interests of the child, not a contract signed years earlier. Parents cannot agree in advance to waive or cap child support, because that right belongs to the child. State formulas set the minimum amount of support, and any clause attempting to reduce payments below that floor is void.
ERISA Retirement Survivor Benefits
For 401(k) plans, pensions, and other retirement accounts governed by the Employee Retirement Income Security Act, a prenuptial agreement cannot waive a spouse’s right to survivor benefits. Federal law requires that a valid waiver of survivor annuity rights come from a “spouse,” and someone who hasn’t married you yet doesn’t qualify.2Office of the Law Revision Counsel. 29 USC 1055 – Requirement of Joint and Survivor Annuity and Preretirement Survivor Annuity The waiver must be in writing, must acknowledge the effect of giving up those benefits, and must be witnessed by a plan representative or notary public. Treasury regulations reinforce this by providing that survivor annuity protections cannot be eliminated or reduced by the form of contract used.3eCFR. 26 CFR 1.401(a)-20 – Requirements of Qualified Joint and Survivor Annuity and Qualified Preretirement Survivor Annuity A prenup can state the intent for your spouse to waive those benefits after the wedding, but the actual waiver paperwork has to happen post-marriage to be valid.
Social Security
Federal law flatly prohibits the transfer, assignment, or garnishment of Social Security payments, and no other law can override that protection.4Office of the Law Revision Counsel. 42 USC 407 – Assignment of Benefits A marriage contract clause purporting to waive a spouse’s future Social Security survivor benefits is unenforceable.
Lifestyle Clauses and Illegal Provisions
Provisions that penalize personal behavior or regulate intimacy between spouses are unenforceable in most jurisdictions. Courts view marriage contracts as financial instruments, and clauses governing household chores, personal appearance, or relations with in-laws are considered contrary to public policy. Any provision that requires or encourages illegal activity is automatically void.
Tax Treatment the Contract Can’t Change
A marriage contract can divide property between spouses, but it cannot change how the IRS treats that property. If you file a joint tax return, both spouses are jointly and severally liable for the full tax bill. The IRS has stated explicitly that this remains true even when a divorce decree assigns tax responsibility to one spouse.5Internal Revenue Service. Innocent Spouse Relief A prenuptial clause saying “each spouse pays taxes on their own income” is binding between the two of you, but the IRS can still collect from either spouse if a joint return was filed.
Innocent spouse relief remains available regardless of what the contract says. The IRS evaluates relief requests on its own criteria, and a private agreement cannot waive or restrict a spouse’s right to seek that relief.5Internal Revenue Service. Innocent Spouse Relief In the nine community property states, the IRS looks to state law to determine property rights, so whether your contract’s “separate property” designation holds up for tax purposes depends on whether your state recognizes it.6Internal Revenue Service. Income Reporting Considerations of Community Property
What Makes the Coverage Hold Up
Any provision in a marriage contract is only as strong as the process behind it. A few baseline requirements determine whether a court will actually enforce what the document covers.
Full financial disclosure. Each spouse must put their full financial picture on the table before signing: assets, liabilities, and income, documented and attached as a Schedule of Assets and Liabilities. Hiding an account or understating a debt gives the other spouse grounds to challenge the entire agreement years later. The UPAA specifically lists inadequate financial disclosure as a basis for refusing enforcement.1American Academy of Matrimonial Lawyers. The Uniform Premarital Agreement Act and Its Variations Throughout the States
Writing and voluntary consent. The contract must be in writing and signed by both parties. Courts will not enforce oral promises. Timing matters. Presenting a contract the night before the wedding creates strong grounds for the other person to argue they were pressured. Legal professionals generally recommend starting the process at least six months before the wedding.
Not unconscionable at signing. Under the UPAA, a contract is unenforceable if the challenger shows both that it was unconscionable when signed and that they weren’t given fair financial disclosure.1American Academy of Matrimonial Lawyers. The Uniform Premarital Agreement Act and Its Variations Throughout the States Unconscionability is measured at the time of execution, not at divorce. An agreement that looks lopsided ten years later isn’t automatically unconscionable if conditions were different when both parties signed.
Independent legal counsel. Separate attorneys aren’t technically required in every state, but when each person has their own counsel, the contract carries a strong presumption that both sides understood what they were giving up. Without separate lawyers, the unrepresented spouse has a far easier time arguing later that they didn’t grasp the consequences.
Prenup Versus Postnup Coverage
The provisions available in both types of contract are the same, but courts evaluate them differently. Postnuptial agreements face stricter scrutiny because spouses owe each other a fiduciary duty once they’re married. Before the wedding, you’re two independent people negotiating at arm’s length. After the wedding, you’re legal partners with an obligation of good faith and transparency. That heightened duty means a court will look more carefully at whether one spouse used their position to pressure the other.
The practical consequence: postnuptial agreements need even cleaner documentation, including thorough disclosure, clear evidence of voluntary signing, and independent counsel for both sides. Courts are more willing to invalidate a postnup on fairness grounds than they would be for the same terms in a prenup. If a particular provision matters to you, signing it before the wedding generally gives it a stronger chance of surviving a later challenge.