Is a Postnup as Good as a Prenup?

Short Answer: A postnuptial agreement (postnup) can be just as legally binding as a prenuptial agreement (prenup) in California—but it’s held to a higher standard of fairness and disclosure because it’s signed after marriage. While both serve similar purposes, courts scrutinize postnups more carefully, making them slightly riskier and harder to enforce if not properly drafted.

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What’s the Difference Between a Prenup and a Postnup?

Feature	Prenup	Postnup
When it’s signed	Before marriage	After marriage
Legal standard	Contract law + UPAA	Contract law + fiduciary duty
Scrutiny by courts	Standard fairness review	Higher scrutiny due to spousal duty
Typical uses	Asset protection before marriage	Mid-marriage financial planning or repair

What Does a Postnup Do?

Just like a prenup, a postnup can:

• Define separate vs. community property

• Allocate debt responsibilities

• Protect business interests

• Waive or limit spousal support (with strict requirements)

• Address inheritance rights and estate planning goals

But unlike a prenup, a postnup is created when spouses already owe each other a fiduciary duty under California Family Code § 721. That means both parties must act in good faith and with full transparency.

When Is a Postnup Useful?

• You didn’t sign a prenup, but now you want to define financial boundaries

• You’ve received an inheritance or started a business after marriage

• You’re reconciling after marital issues and want to rebuild trust

• One spouse has taken on significant debt

• You’re updating your estate plan in a blended family

Is a Postnup Enforceable in California?

Yes—but enforcement is more complex than with prenups. For a California postnup to be valid:

1. It must be in writing and signed by both spouses

2. Full financial disclosure must be provided

3. Independent legal counsel for both spouses is highly recommended

4. No coercion, fraud, or undue influence can be present

5. The terms must be fair and not unconscionable

Courts may be more skeptical of postnups—especially if one spouse gives up rights without clear benefits or protections in return.

Advantages of a Postnup

• Allows financial clarity and structure after marriage

• Useful for evolving situations (e.g., children, inheritance, career changes)

• Can prevent future disputes or divorce battles

• Supports estate planning goals

Risks and Drawbacks

• Harder to enforce than a prenup

• Subject to stricter legal scrutiny

• May cause emotional tension in the relationship

• Can be challenged more easily if one spouse feels pressured or unfairly treated

Can a Postnup Replace a Prenup?

A postnup can serve many of the same legal purposes—but it’s not always a perfect substitute. A prenup has the advantage of being signed before marital duties apply and typically faces less skepticism from courts.

Best practice: If you’re not yet married, a prenup is usually the safer, stronger option.

Let Moravec, Varga & Mooney Guide You Through It

Whether you're exploring a prenup or postnup, we’ll help you:

• Draft a clear, enforceable agreement

• Comply with California law and disclosure requirements

• Protect your family, finances, and long-term goals

Contact us today to schedule a confidential consultation and start building the right agreement for your relationship.