The wedding is over and the paperwork never happened. Now you want the agreement you meant to sign.
Not legal advice. This article is general information only. Prenup laws differ by state and change over time. Consult a licensed attorney in your state before acting on anything here.
Here is the short answer. You cannot get a prenup after marriage, because a prenup is defined by its timing rather than its contents.
What you can get is a postnup, and it does the same job. It just has a harder time surviving a court.
That last part is what almost nobody tells you, and it is the whole reason this question matters.
Key Takeaways
- A prenup must be signed before the wedding. After that, the same document is a postnup, and it is judged by different rules.
- A postnup can cover the same ground as a prenup: property, debt, and spousal support. The limits on child support and custody are identical.
- Postnups are harder to enforce. In Massachusetts the spouse who wants to enforce one carries the burden of proving it was fair, which is the reverse of the prenup rule.
- A prenup is enforceable without consideration. A postnup at common law usually needs it, and staying in the marriage does not count.
- Only two states, Colorado and North Dakota, have a statute covering postnups. Everywhere else it is case law.
- Ohio banned postnups outright until March 23, 2023. Louisiana still requires a judge to approve one.
- The window closes once divorce is anticipated. At that point you are writing a separation agreement, governed by other law.
Can You Get a Prenup After Marriage?
No, and the reason is definitional rather than legal hair-splitting.
The Uniform Premarital Agreement Act defines a prenup as “an agreement between prospective spouses made in contemplation of marriage and to be effective upon marriage.”
Prospective is the operative word. Once you are married, you are no longer prospective spouses, and the Act stops applying to you.
The same Act says so directly in its own commentary: “postnuptial or separation agreements are outside the scope of this Act.”
So the answer is the same whether you are asking a week after the wedding or twenty years in.
The prenup ship has sailed. The postnup is still in the harbour.
Prenup vs Postnup: What Actually Changes
Both documents answer the same questions. Who owns what, who owes what, and what happens to support if the marriage ends.
What changes is the legal machinery behind them.
A prenup runs on a statute in most states, with a settled national standard. A postnup, in 48 states, runs on whatever the courts there have decided, and the Uniform Law Commission is blunt about how that turned out.
Its 2012 drafting note reads: “The situation regarding marital agreements has been far less settled and consistent. Some states have neither case law nor legislation, while the remaining states have created a wide range of approaches.”
| Feature | Prenup | Postnup |
|---|---|---|
| When signed | Before the wedding | During the marriage |
| When effective | On marriage | On signing |
| Governing law | Statute in most states (UPAA) | Case law in 48 states |
| Consideration needed | No, marriage itself counts | Usually yes, at common law |
| Who bears the burden | The spouse attacking it | The spouse enforcing it, in some states |
| Can cover property, debt, support | Yes | Yes |
| Can waive child support | No | No |
Is a Postnup as Good as a Prenup?
Honestly, no. It is the same deal on paper and a weaker one in court.
Three things work against it, and each one is worth understanding before you sign.
The Burden Flips
With a prenup, the spouse trying to escape it has to prove something is wrong with it.
With a postnup in Massachusetts, that flips. The Supreme Judicial Court held in Ansin v. Craven-Ansin that “the spouse seeking to enforce the agreement shall bear the burden of satisfying these criteria.”
The court was explicit that this is not the prenup rule: “We do not accept the husband’s suggestion that the standard applicable to marital agreements should be the same as the one applicable to premarital agreements.”
Its reasoning cuts to why. “Before marriage, the parties have greater freedom to reject an unsatisfactory premarital contract.”
Put plainly, you can walk away from a fiancé. Walking away from a spouse costs a divorce.
That imbalance is exactly what worries judges. The same opinion describes postnup negotiations as “pregnant with the opportunity for one party to use the threat of dissolution ‘to bargain themselves into positions of advantage.'”
The Consideration Problem
This one sinks more postnups than people expect, and it is pure contract law.
Every contract needs consideration, meaning both sides give something up. A prenup gets a free pass because the marriage itself is the consideration, and the uniform acts say so outright: it “is enforceable without consideration.”
A postnup has no such luck. You are already married, so the marriage cannot pay for the promise twice.
The Tennessee Supreme Court laid it out in Bratton v. Bratton: “with a postnuptial agreement, the marriage itself cannot act as sufficient consideration because past consideration cannot support a current promise.”
The court then voided the agreement in front of it, and the detail is worth sitting with. The wife had promised not to leave.
That was not enough: “Ms. Bratton’s promise not to leave her husband is clearly not consideration for the agreement.” Nor was the happier marriage that followed, which the court dismissed as “domestic tranquility” rather than payment.
There is a real exception. Where a separation is genuinely imminent and the agreement is what brings the couple back together, the promise to reconcile does count.
Spouses Owe Each Other More Than Strangers Do
An engaged couple negotiates at arm’s length. A married couple does not.
The Uniform Law Commission explains the consequence: “parties already married are in a fiduciary relationship in a way that parties about to marry, and considering a premarital agreement, are not.”
Ansin puts it more sharply, noting that the disclosure duty “is greater with respect to marital agreements because each spouse owes a duty of absolute fidelity to the other.”
The practical translation is that a half-hearted financial disclosure that might survive in a prenup will not survive in a postnup.
Where the Rules Change by State
This is where the postnup story stops being national and starts depending on your zip code.
Only Two States Have a Postnup Statute
The Uniform Premarital and Marital Agreements Act of 2012 was written to fix exactly this mess, and it covers both documents under one standard.
Its drafters said why: “A number of states currently treat premarital agreements and marital agreements under different legal standards, with higher burdens on those who wish to enforce marital agreements.”
Two states adopted it. Colorado, effective July 1, 2014, and North Dakota.
If you are in either one, your postnup is held to the same standard as a prenup. If you are in the other 48, it is not.
Ohio Only Legalized Postnups in 2023
Ohio is the sharpest example of how recent this law is.
Until Senate Bill 210 took effect on March 23, 2023, postnups were simply void there. An Ohio appeals court stated it flatly in 2024: “Prior to the effective date of S.B. 210 on March 23, 2023, postnuptial agreements were not valid in Ohio.”
The old statute barred spouses from contracting to “alter their legal relations,” with a narrow exception for an immediate separation.
Since a postnup assumes you are staying together, it fell outside the exception and died there. Anyone quoting Ohio postnup advice written before 2023 is quoting a ban.
Louisiana Needs a Judge to Approve It
Louisiana is the one state where signing is not the end of the process.
Civil Code article 2329 lets spouses change their matrimonial regime during marriage “only upon a joint petition and a finding by the court that this serves their best interests and that they understand the governing principles and rules.”
The Louisiana Supreme Court confirmed the point in Acurio v. Acurio: “court approval would be required to enter into a matrimonial agreement post-nuptially.”
The court was candid that the difficulty is deliberate, describing a legislative choice “to make it onerous to waive one’s community property rights.”
Other States Simply Look Harder
Most states sit between these poles. They allow postnups and then scrutinize them more closely than prenups.
Massachusetts and Connecticut are the two the Uniform Law Commission singles out as the leading examples of that approach, through Ansin and Bedrick v. Bedrick.
The takeaway is not that postnups fail. It is that the same paperwork that passes before a wedding gets a longer look after one.
What a Postnup Can and Cannot Do
On subject matter, a postnup reaches everything a prenup reaches.
It can characterize property as separate or marital, assign responsibility for debts, waive or set spousal support, and handle what happens at death.
The limits are the same ones that bind a prenup, and they are absolute.
Child support cannot be reduced or waived, because the right belongs to the child rather than the parents. Custody terms do not bind a court, which decides by the best interests of the child at the time of the dispute.
The uniform act adds three further limits that apply equally to both documents. An agreement cannot restrict a domestic violence victim’s remedies, cannot rewrite the grounds for divorce, and cannot penalize a spouse for filing.
Can You Change or Cancel a Prenup After Marriage?
Yes, and this is the one area where being married is not a disadvantage.
A prenup is a contract, and both parties can amend or revoke it by written agreement. Amending it after the wedding makes the amendment a marital agreement, which means the postnup rules apply to the change.
Cancelling entirely is cleaner than rewriting. A revocation gives nothing to either side, so the consideration and fairness problems that sink one-sided postnups mostly fall away.
What you cannot do is change it unilaterally. A prenup you now regret is not void because you regret it.
When a Postnup Makes Sense
The strongest postnups are the ones responding to something that actually changed.
One spouse starts a business and the other wants clarity on whether it counts as marital property. An inheritance lands.
One partner leaves the workforce to raise children, which is the moment their financial exposure changes most and the moment the lower-earning spouse should be asking for terms.
Debt is another common trigger, especially where one spouse’s obligations are growing and the other wants to be walled off from them.
The weakest postnups are the ones where nothing changed except that one spouse now has leverage. Those are the agreements courts are looking for.
The Window Closes Once Divorce Is on the Table
A postnup is for spouses who intend to stay married. That is not a mood, it is a legal category.
The uniform act excludes agreements signed when a divorce or separation “is anticipated or pending.” At that point the document is a separation agreement and different law governs it.
The practical lesson is that a postnup is not a tool for managing a marriage that is already ending. Sign it while things are stable or do not sign it at all.
How to Get a Postnup After Marriage
The mechanics are close to a prenup, with two extra steps that carry most of the risk.
- Raise it when nothing is on fire. A postnup negotiated during a rough patch invites the argument that it was signed under the threat of divorce.
- Disclose everything, in writing. Attach schedules of assets, debts, and income for both spouses. The fiduciary duty between spouses sets the bar higher than it was before the wedding.
- Build in real consideration. Each side has to give something up. Mutual waivers of claims against each other’s property are the classic structure, and courts have upheld them.
- Get separate counsel. One lawyer cannot represent both of you, and shared representation is a gift to whoever wants the agreement voided later.
- Sign and notarize. Follow your state’s formalities. In Louisiana, add a joint petition and a judge.
The two steps people skip are consideration and disclosure, which happen to be the two that sank the agreements in the cases above.
What It Costs and Where to Get One
Postnup pricing tracks prenup pricing. Attorney-drafted agreements generally start around $1,500 to $5,000 per person and climb with complexity.
Online platforms cover both documents at a fraction of that. HelloPrenup handles prenups and postnups at a flat $599 per couple across 47 states plus DC, and our review sets out where it works and where it does not.
Here is the caveat that matters more for a postnup than a prenup. Because the enforcement standard is stricter, the parts a platform cannot supply are the parts most likely to be attacked later.
That means real consideration flowing both ways, disclosure thorough enough to survive a fiduciary duty, and separate counsel for each spouse.
Drafting online and paying an attorney to review the result is a reasonable middle path. Skipping the review entirely is a worse bet on a postnup than it is on a prenup.
If you have not married yet, none of this applies to you, and our prenup hub covers requirements in all 50 states. Sign before the wedding and you get the easier document.
Final Thoughts
The honest summary is that a postnup is the second-best version of a document you can no longer get.
It reaches the same subjects and answers the same questions. It just asks more of you: consideration on both sides, fuller disclosure, and in some states a judge.
None of that makes a postnup a bad idea. A well-built postnup beats no agreement, and for couples whose finances changed after the wedding it is the only option on the table.
It does mean the margin for sloppiness is thinner. The prenup forgives a rushed job more readily than the postnup does.
If the wedding is still ahead of you, that is the cheapest legal advice on this page. Sign it now.
Sources
- Uniform Premarital Agreement Act (1983), Section 1 and Prefatory Note, Uniform Law Commission
- Uniform Premarital and Marital Agreements Act (2012), Sections 2, 3, 6, 7 and 10, with Prefatory Note and Comments, Uniform Law Commission
- Ansin v. Craven-Ansin, 457 Mass. 283, 929 N.E.2d 955 (2010)
- Bratton v. Bratton, 136 S.W.3d 595 (Tenn. 2004)
- Acurio v. Acurio, 2016-1395, 224 So. 3d 935 (La. 2017), quoting La. Civ. Code art. 2329
- Pettitt v. Schaffner, 2024-Ohio-5180 (Ohio Ct. App. 2024), on Senate Bill 210 and former R.C. 3103.06
- Hahn v. Farmakis-King, 2024-Ohio-786, 238 N.E.3d 147 (Ohio Ct. App. 2024)
- Colorado Revised Statutes Sections 14-2-301 to 14-2-313 (UPMAA, effective July 1, 2014); North Dakota Century Code chapter 14-03.2
- Bedrick v. Bedrick, 301 Conn. 548, 17 A.3d 17 (2011)