Quick Answer A postnuptial agreement is a written contract between spouses entered into after marriage. It addresses the same issues as a prenuptial agreement, including property division, debt allocation, and spousal support, but is signed during the marriage rather than before. California enforces postnuptial agreements but applies stricter scrutiny than prenups because spouses owe each other a fiduciary duty under California Family Code section 721. Any agreement that disadvantages one spouse must comply with this duty. Postnups are commonly used after reconciliation, when financial circumstances change significantly, when one spouse receives a large inheritance or business interest, or when the spouses want to formalize an arrangement that was informal during the early marriage. The cost of a properly drafted postnup ranges from $2,500 to $15,000 depending on complexity.
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What Is a Postnuptial Agreement
A postnuptial agreement, also called a postnup or post marital agreement, is a written contract entered into by two people after they are already married. The agreement addresses how the couple’s finances will be handled during the marriage and in the event of divorce or death.
Postnups can serve many purposes including protecting separate property, defining how new income or assets will be characterized, providing for one spouse who is leaving the workforce, or formalizing an arrangement when one spouse receives a large inheritance. The contract gives the spouses the ability to customize the default rules of California family law to suit their specific circumstances.
Postnuptial agreements are valid in California but face higher scrutiny than prenuptial agreements. The key difference is timing. Before marriage, the parties are negotiating at arm’s length as two individuals planning to commit to each other. After marriage, they are spouses with a legal fiduciary duty to each other. This changes the legal analysis significantly.
Postnup vs Prenup Key Differences
| Feature | Prenuptial Agreement | Postnuptial Agreement |
| Timing | Before marriage | After marriage |
| Governing law | UPAA (FC sections 1610-1617) | FC sections 850-853, 721 |
| Fiduciary duty | Not yet between spouses | Exists between spouses |
| 7 day waiting period | Required | Not statutorily required |
| Court scrutiny | Strict but defined | Higher fiduciary duty review |
| Typical cost | $1,500 to $20,000+ | $2,500 to $15,000+ |
When to Consider a Postnup
Couples consider postnuptial agreements in several common situations:
Reconciliation After Separation
Couples who have separated and decided to reconcile often use a postnup to address issues that led to the separation. The agreement might restructure finances, establish new expectations, or provide protections each spouse needs to feel safe returning to the marriage.
Significant Change in Circumstances
Major financial changes during the marriage can justify a postnup. Examples include one spouse inheriting a substantial sum, one spouse starting or selling a successful business, one spouse winning a lottery or other windfall, or one spouse leaving the workforce to care for children or elderly parents.
Formalizing Pre Existing Informal Arrangements
Some couples make informal financial arrangements during marriage that they later want to formalize. A postnup can document these arrangements in a legally enforceable form.
Addressing Issues Not Handled in Prenup
Couples with prenuptial agreements sometimes need a postnup to address issues that arose during marriage. For example, the original prenup may not have anticipated certain assets or business changes that have since occurred.
Estate Planning Coordination
A postnup can coordinate with estate planning documents. When one spouse has children from a previous relationship and wants to ensure those children inherit certain assets, a postnup can confirm what is separate property and what the other spouse will not claim.
The Fiduciary Duty Issue
California Family Code section 721(b) imposes a fiduciary duty between spouses, which significantly affects postnuptial agreements. A board-certified family law specialist can help navigate the fiduciary duty issues that make postnups more complex than prenups.
The fiduciary duty includes:
- Highest good faith and fair dealing
- Each spouse cannot take unfair advantage of the other
- Full disclosure of all material facts
- Avoidance of any transaction that benefits one spouse at the expense of the other
In re Marriage of Burkle (2006) 139 Cal.App.4th 712 confirmed that the fiduciary duty applies to postnuptial agreements. Any agreement that significantly benefits one spouse over the other requires evidence that the disadvantaged spouse fully understood the agreement and entered into it voluntarily with full knowledge.
Presumption of Undue Influence
When a postnuptial agreement benefits one spouse over the other, courts may apply a presumption of undue influence. The benefiting spouse must rebut this presumption by showing that the agreement was entered into freely, with full disclosure, and without taking unfair advantage.
Enforceability Requirements
For a postnuptial agreement to be enforceable in California, several requirements must be met:
- Written agreement signed by both spouses
- Full and complete financial disclosure by both spouses
- Both spouses sign voluntarily without duress or undue influence
- Both spouses have the opportunity to consult independent counsel
- Agreement is fair and not unconscionable
- Agreement complies with fiduciary duty under California Family Code section 721
- Any transfer or transmutation of property complies with California Family Code section 852
Transmutation Rules
If the postnuptial agreement changes the character of property (for example, converting community property to separate property or vice versa), California Family Code section 852 imposes additional requirements. The transmutation must be expressly stated in writing by the spouse whose interest is adversely affected. Mere implication is not enough. The writing must clearly identify what property is being transmuted and what the new characterization will be.
Required Financial Disclosures
Like prenups, postnups require full financial disclosure. Both spouses must disclose:
- All real estate, including separate and community property
- All bank accounts, investment accounts, and retirement accounts
- All business interests, including separate and community
- All vehicles and significant personal property
- All debts including mortgages, credit cards, and other obligations
- All sources of income and amount
- Tax returns for recent years
- Expected inheritances or business interests
Disclosure is typically accomplished by attaching detailed financial statements to the agreement. The disclosure should be more thorough than for a prenup because the fiduciary duty raises the standard.
Common Postnup Provisions
Typical provisions in California postnuptial agreements include:
Property Provisions
- Identification of existing separate property
- Treatment of future income and acquisitions
- Treatment of appreciation of separate or community property
- Specific assets like the family home
- Treatment of business interests
Debt Provisions
- Allocation of existing debts
- How future debts will be allocated
- Each spouse’s responsibility for specific debts
Spousal Support Provisions
- Waiver, limitation, or specification of spousal support amount in event of divorce
- Conditions affecting support obligations
Reconciliation Provisions
- Terms for living together after a separation
- Communication and conflict resolution arrangements
- Financial protections in event of future separation
What a Postnup Cannot Cover
Like prenups, postnups cannot:
- Waive or limit child support obligations
- Determine child custody (this is decided in the best interest of the child)
- Violate public policy
- Require sexual or other personal behavior
- Penalize one party for choosing divorce
- Limit religious practice
Any provision attempting to address these matters is unenforceable, but it does not necessarily invalidate the entire agreement. Courts can sever unenforceable provisions and enforce the rest.
Postnups After Reconciliation
Reconciliation postnups are a common use case. When spouses have separated and decide to give the marriage another chance, a postnup can address issues that led to the separation and provide a fresh start. Common reconciliation postnup provisions include:
- Updated financial arrangements reflecting changes during separation
- Specific behavior or communication requirements
- Counseling or therapy commitments
- Conditions that would trigger immediate divorce
- Financial penalties for breaching the agreement
- Provisions for future separation if reconciliation does not work
Reconciliation postnups are sometimes called marriage repair agreements or reconciliation agreements. The key purpose is providing both spouses confidence that their interests are protected as they attempt to rebuild the marriage.
Postnups and Estate Planning
Postnuptial agreements often coordinate closely with estate planning. Both documents address what happens to assets at death. They must be consistent to avoid conflicts. Common coordination issues include:
- Identifying which assets are separate property protected from elective share claims
- Providing for children from prior relationships
- Coordinating with trusts and other estate planning vehicles
- Addressing life insurance and retirement account beneficiaries
- Confirming gift and inheritance protections
Working with both a family law attorney and an estate planning attorney is often advisable when significant assets are involved. The two attorneys can ensure the documents work together without conflict.
Cost of a Postnuptial Agreement
Postnup costs vary based on complexity:
- Simple postnup: $2,500 to $5,000
- Standard postnup with moderate complexity: $5,000 to $10,000
- Complex postnup with significant assets, businesses, or trusts: $10,000 to $25,000
- Very high net worth or international elements: $25,000 to $75,000+
These figures include independent counsel for both spouses. The fiduciary duty considerations make postnups generally more expensive than prenups for similar complexity.
Frequently Asked Questions
Q: What is the difference between a prenup and a postnup?
A: The main difference is timing. A prenup is signed before marriage, while a postnup is signed after marriage. Both address similar issues including property division, debt allocation, and spousal support. The legal scrutiny differs. Prenups are governed by the Uniform Premarital Agreement Act under California Family Code sections 1610 through 1617 with specific procedural requirements. Postnups are subject to the fiduciary duty between spouses under California Family Code section 721, which imposes a higher standard of fairness.
Q: Are postnuptial agreements legal in California?
A: Yes. California enforces postnuptial agreements, but applies stricter scrutiny than prenuptial agreements because of the fiduciary duty between spouses under California Family Code section 721. The agreement must comply with all statutory requirements including written form, full disclosure, voluntary signing, and fairness. The benefiting spouse may need to rebut a presumption of undue influence if the agreement significantly favors one party.
Q: When should we get a postnuptial agreement?
A: Common situations include after reconciliation following a separation, when one spouse receives a significant inheritance or business interest, when financial circumstances change significantly, when one spouse leaves the workforce to care for children or elderly parents, when there is a desire to formalize a pre existing informal arrangement, or when the original prenup did not anticipate current situations. The postnup is particularly useful when the spouses want to preserve specific assets or provide for children from previous relationships.
Q: Can a postnup waive spousal support?
A: Yes, but the waiver receives careful scrutiny. The waiving spouse must be represented by independent counsel, must have full financial disclosure, and the waiver must not be unconscionable at the time of enforcement. The fiduciary duty between spouses means the court will examine whether the waiver was the result of overreaching by the supported spouse. A spousal support waiver in a postnup is harder to enforce than the same waiver in a prenup.
Q: Do both spouses need separate lawyers?
A: Independent counsel for both spouses is essentially required for postnuptial agreements to be enforceable. Without independent counsel, the disadvantaged spouse can argue they did not understand the agreement or were taken advantage of. Even when independent counsel is not strictly required, courts apply far more scrutiny to postnups signed without dual representation. The cost of independent counsel is far less than the cost of an invalidated agreement.
Q: Can a postnup be invalidated?
A: Yes. Postnups can be invalidated if there was inadequate financial disclosure, if the agreement violates the fiduciary duty between spouses, if signed under duress or undue influence, if grossly unfair to one spouse, if it violates public policy, or if it attempts to address child support or custody. Courts scrutinize postnups carefully because the existing marital relationship creates greater opportunity for overreaching by one spouse against the other.
Q: How much does a postnuptial agreement cost?
A: Simple postnups cost $2,500 to $5,000. Standard postnups cost $5,000 to $10,000. Complex postnups with significant assets, businesses, or trusts cost $10,000 to $25,000. Very high net worth or international elements can push the cost to $25,000 to $75,000 or more. These figures include independent counsel for both spouses. The cost is small compared to the protection provided and is typically a fraction of what contested property litigation in a divorce would cost.
Q: Can a postnup be changed later?
A: Yes. Postnuptial agreements can be modified or terminated by mutual written agreement. The modification must comply with the same requirements as the original agreement, including full disclosure, voluntary signing, and fiduciary duty considerations. Any modification that disadvantages one spouse will face the same scrutiny as the original agreement. The modification or termination must be in writing; oral modifications are not enforceable.
Bottom Line
A postnuptial agreement is a valuable tool when circumstances have changed during a marriage or when spouses want to formalize their financial relationship. California enforces postnups but applies stricter scrutiny than prenups because of the fiduciary duty between spouses under California Family Code section 721. Independent counsel for both spouses is essentially required. Full financial disclosure is critical. The agreement must be fair and not unconscionable. Common uses include after reconciliation, after significant financial changes, when one spouse receives an inheritance, and when coordinating with estate planning.
If you are considering a postnuptial agreement, a free consultation with a board-certified family law specialist can help you understand the requirements and protections specific to your situation.
About the Author
Donald Glen Haslam, Esq. is a Board-Certified Family Law Specialist by the California State Bar Board of Legal Specialization and a senior partner at Haslam & Thorne, LLP in Ontario, California. He has practiced family law exclusively for over 40 years, representing families throughout San Bernardino County and the Inland Empire. Reviewed by Brian George Thorne, Esq., Board-Certified Family Law Specialist.
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Disclaimer: This article is for general informational purposes only and does not constitute legal advice. Postnuptial agreement law has strict requirements that vary by state. For advice specific to your situation, consult with a licensed family law attorney. Reading this article does not create an attorney-client relationship with Haslam & Thorne, LLP