Are Postnups Enforceable in Massachusetts? The 5 Ansin Tests

Is a postnuptial agreement enforceable in Massachusetts?

Yes. A Massachusetts postnuptial agreement can be enforced if it meets the Ansin criteria under the careful review a judge applies when one spouse challenges it. The agreement has to pass on both process and substance.

In Ansin v. Craven-Ansin, the Supreme Judicial Court (SJC) adopted the American Law Institute's definition. A postnuptial, or "marital," agreement is an "agreement between spouses who plan to continue their marriage that alters or confirms the legal rights and obligations that would otherwise arise" under divorce law. The court uses "premarital" for what most people call a prenup and "marital" for a postnup.

Massachusetts law treats three kinds of spousal agreements differently:

• Premarital (antenuptial) agreements are signed before the wedding.
• Marital (postnuptial) agreements are signed during a marriage that both spouses intend to continue.
• Separation agreements are signed when a couple has split up and intends to divorce.

The question of whether postnups could be enforced stayed open for nearly two decades. In Fogg v. Fogg (1991), the SJC struck down a marital agreement on fraud grounds and expressly left "to another day" whether a fraud-free agreement could be valid. Ansin answered that question in 2010. The Massachusetts Trial Court Law Libraries still list Ansin as the leading case on post-nuptial agreements.

The SJC chose a heightened standard for three reasons:

1. Bargaining position. The court acknowledged that marital agreements are "not the product of classic arm's length bargaining." In other words, spouses aren't negotiating as strangers would.
2. Pressure to sign. Commentary on the decision points out that the potential cost of refusing, the loss of an ongoing marriage, is much greater than it is before a wedding.
3. No built-in disclosure. A divorce comes with court-ordered financial disclosure under Supplemental Probate and Family Court Rule 401. A private marital agreement doesn't.

None of this makes a postnup a defensive document. Many couples use one to get clear on money after a change in circumstances, such as an inheritance, a new business, or one spouse stepping back from work. The heightened scrutiny means the process should be transparent and balanced from the start.

The five Ansin tests courts apply to a Massachusetts postnuptial agreement

Before approving a marital agreement, a Massachusetts judge determines "at a minimum" whether (1) each party had an opportunity to obtain separate legal counsel of their own choosing; (2) there was fraud or coercion in obtaining the agreement; (3) all assets were fully disclosed by both parties before signing; (4) each spouse knowingly and explicitly agreed in writing to waive the right to a judicial equitable division of assets and all marital rights in the event of a divorce; and (5) the terms are fair and reasonable at the time of execution and at the time of divorce (457 Mass. at 289-291).

Here's how the Ansin agreement itself met each test:

Who carries the burden of proof

If one spouse challenges the agreement, the spouse seeking to enforce it must satisfy all of these criteria. The SJC tied this rule to the ALI Principles, § 7.04(2), which says a party seeking enforcement "must show that the other party's consent to it was informed and not obtained under duress." Under the general contract rule, the party trying to avoid an agreement usually bears the burden, so Ansin reverses the usual starting point.

The Ansin facts, briefly

Kenneth Ansin and Cheryl Craven-Ansin married in July 1985. After a period of marital difficulty and counseling that began in late 2003, they negotiated and signed a marital agreement in July 2004. Their combined assets were about $19 million at the time. The husband filed for divorce in November 2006, after 21 years of marriage. The Probate and Family Court enforced the agreement, and the SJC affirmed.

Context and "great latitude"

Judges look at the whole context in which the agreement was reached. They allow "great latitude for agreements reached where each party is represented by separate counsel of their own choosing" (457 Mass. at 297). The Appeals Court has quoted this language in later cases, including K.G.S. v. D.S. (2019).

A later application: Connors v. Connors (2018)

In Connors v. Connors, the Appeals Court agreed that the husband signed freely. He was a sophisticated businessman who signed "of his own free will and with the advice of counsel." Even so, the court sent the case back because the trial judge hadn't clearly found that the terms were fair and reasonable at the time of the divorce. The fifth test really does apply at two separate points in time.

Difference between a prenup and a postnup in Massachusetts

A prenup is signed before marriage and reviewed under DeMatteo v. DeMatteo (2002). A postnup is signed during marriage and reviewed under the stricter Ansin standard. The two agreements can cover similar subjects, but courts evaluate them differently.

The prenup standard comes from DeMatteo v. DeMatteo, 436 Mass. 18. There the SJC said that many valid premarital agreements "may be one sided" and still be enforced. Postnups get less room for that kind of imbalance. Spouses already have legal and financial obligations to each other, and agreeing to sign in order to keep a marriage together is a different kind of pressure than bargaining before a wedding.

Massachusetts hasn't adopted the Uniform Premarital Agreement Act. Its prenup rules come from its own statutes and case law, as the Oakclause state comparison notes.

Decision point: Maybe you didn't sign a prenup, or your circumstances have changed since the wedding (an inheritance, a business, a career shift). You can still set out expectations through a postnup. Just plan for the higher standard.

Whichever agreement fits your timing, the goal is the same: shared clarity. As Michael C. Cotugno, Esq., Managing Partner, Neptune Legal, puts it: "A premarital agreement doesn't have to be a wedge between partners or a necessary evil that protects assets at the expense of trust and intimacy."

Do you need a lawyer for a postnup in Massachusetts?

Massachusetts requires that each spouse have the opportunity to obtain separate counsel of their own choosing. It doesn't strictly require that both spouses actually hire a lawyer. In practice, though, separate counsel carries real weight in how a court reviews the agreement.

Independent counsel for each partner is highly recommended for an enforceable prenup, and the same reasoning applies with even more force to a postnup. Separate counsel supports several Ansin tests at once:

• Coercion. Lengthy negotiations through two lawyers suggest the agreement was freely made.
• Waiver. A lawyer can explain what each spouse is giving up under G.L. c. 208, § 34.
• Fairness. Courts give "great latitude" to agreements negotiated with separate counsel.

Connors shows how this plays out. The husband first worked without a lawyer. At the wife's insistence, he hired counsel, who then took part in a lengthy negotiation that ran from 2009 to 2011. When the husband later claimed duress, the courts found he had signed freely and with the advice of counsel.

What you can do together: talk through your goals, gather account statements and records, list your assets and debts, and agree on your priorities.

What calls for a qualified Massachusetts attorney: drafting the waiver language, assessing fairness against the § 34 factors, and advising each spouse individually about their own rights.

Neptune offers a lawyer-led online process for prenups and postnups. If both spouses use Neptune-network lawyers, each spouse has an independent attorney, and each spouse chooses their own. No lawyer or service can guarantee how a court will rule. The Ansin tests still apply to the finished agreement.

How much does a postnup cost in Massachusetts?

Published Massachusetts estimates run from a few hundred dollars for a review to several thousand dollars for a complex agreement. Your total depends on how complex your finances are and whether each spouse retains separate counsel.

The figures below come from Divorce.law's Massachusetts postnuptial guide, which cites 2026 marketplace data:

Treat these numbers as rough benchmarks. They come from a single source, and that source doesn't say whether each figure is per attorney or per couple. A couple's total often covers two attorneys: one who drafts the agreement and one who reviews it or negotiates on behalf of the other spouse.

Several cost drivers line up directly with the Ansin tests:

• Hard-to-value assets. Interests like the Ansin family's Florida real estate, which had only a placeholder value, take extra work to describe accurately.
• Depth of disclosure. Full schedules of accounts, retirement funds, trusts, and business interests take time to assemble and review.
• Negotiation rounds. Each additional draft adds attorney time.
• Expert valuation. Business or trust interests may call for an appraiser or valuation expert.

How to plan a postnup that meets the Ansin tests, step by step

The goal is a written agreement that both of you understand, that you negotiated with full information, and that stays fair as your lives change. These steps follow the Ansin criteria in order.

1. Discuss goals together and choose low-pressure timing. Frame the first conversation as an invitation, not a demand. Avoid tying the agreement to deadlines or ultimatums.
2. Each spouse selects their own attorney. Make sure the opportunity for separate counsel is real and documented.
3. [Exchange complete financial disclosure](https://meetneptune.com/blog/prenup-financial-disclosure-hidden-assets). Include assets, debts, income, business and trust interests, and a note on how any hard-to-value asset was estimated.
4. Negotiate drafts through counsel and allow time to reflect. Back-and-forth changes are evidence of a fair process.
5. Include an explicit written waiver. It should show that each spouse understands their rights under G.L. c. 208, § 34 and what they're choosing instead.
6. Test fairness now and later. Ask how the terms would hold up after an illness, an income change, or a drop in asset values. A fixed payment that doesn't depend on asset growth was one reason the Ansin agreement passed.
7. Sign and keep records. Keep copies of the disclosures, the drafts, and the final signed agreement.

When you need a professional: business valuations, complex trusts, and drafting the waiver and fairness terms generally call for a qualified Massachusetts attorney and sometimes a valuation expert. Routine goal-setting and gathering records are things you can do on your own as a couple.

Final checklist

• Each spouse's opportunity for separate counsel is documented
• Financial disclosures are attached to the agreement
• The waiver of equitable division and marital rights is explicit and in writing
• No deadline or ultimatum pressure surrounded the signing
• The terms are fair at signing and hold up under plausible future changes
• You've agreed to revisit the agreement after major life changes