What a Prenup Cannot Decide About Children

What California Law Says About Prenups and Children

Family Code section 1612 is the statute that sets out what a premarital agreement may and may not address. A premarital agreement, as Family Code section 1610 defines it, is "an agreement between prospective spouses made in contemplation of marriage and to be effective upon marriage." Section 1612 then lists the subjects such an agreement can reach, and one it cannot.

On children, subdivision (b) is short and direct:

"The right of a child to support may not be adversely affected by a premarital agreement."

In plain terms, "adversely affected" means made worse. A prenup cannot waive child support, cap it, set it below what the law would otherwise provide, or shift it so a child receives less. Any term that tries to do one of those things runs into subdivision (b).

That one sentence sits against a much longer list in subdivision (a), which covers property, its management, its division on separation or death, wills and trusts, life insurance death benefits, the choice of law, and other matters that do not violate public policy. The pattern is clear once the two subdivisions are read together. Financial terms between the spouses are generally open to agreement. A child's right to support is not something the spouses can bargain over.

Why Child Support Cannot Be Set in a Prenup

The reasoning starts with whose right it is. Child support belongs to the child, not to either parent. A parent cannot sign away something that was never theirs to give, and two adults planning a wedding cannot contract away the rights of a child who may not yet exist.

Timing matters too. California sets child support using a statewide uniform guideline, which Family Code section 4050 describes as adopted to keep the state in compliance with federal child-support guideline rules. That guideline is applied when a support order is actually made. The facts it depends on, such as each parent's finances and how a child's time is shared, cannot be known on a wedding day. A number fixed years in advance would almost certainly bear no relation to the family's real circumstances later.

So a prenup clause that purports to fix, limit or waive child support is unenforceable to the extent it would reduce the child's right. It does not bind either parent, and it does not bind the court.

For a couple in San Diego County, this plays out in a concrete way. If support is ever at issue, the order is made by the Superior Court of California, County of San Diego, applying the same statewide guideline used everywhere in California. Whatever the prenup says about support, the court works from the guideline and the facts in front of it.

Child Custody and Visitation: What a Prenup Cannot Lock In

Custody follows the same logic, through a different statute. Family Code section 3011 tells the court how to decide the best interests of the child. The court must consider, among other relevant factors, the child's health, safety and welfare; any history of abuse; the nature and amount of contact with both parents; and habitual illegal drug use or alcohol abuse by either parent. Section 3011 also bars the court from considering a parent's sex, gender identity, gender expression or sexual orientation in that analysis.

Every one of those factors looks at the family as it is when the case is heard. That is why a premarital agreement cannot predetermine legal custody (who makes decisions about the child), physical custody (where the child lives), a visitation schedule, or any other parenting arrangement. A clause written before marriage, about children not yet born, cannot account for what a court is required to weigh.

Even parents who agree on custody later, in the middle of a case, do not get the last word on their own. Section 3011(a)(5)(B) notes that a custody stipulation must still be in the best interest of the child. A prenup clause has even less footing than that.

When custody or visitation is contested, the court does not simply pick up the prenup. Under Family Code section 3170, if a pleading shows that custody or visitation is contested, "the court shall set the contested issues for mediation." In San Diego County, that mediation is child custody recommending counseling with the court's Family Court Services. Under Family Code section 3183(a), the mediator, called a child custody recommending counselor, may, consistent with local court rules, make a recommendation to the court, if it is first provided in writing to the parties and their attorneys before the hearing. Family Court Services calls this person the Family Court Counselor, and it says that if no agreement is reached, the Family Court Counselor makes a recommendation to the court, and the court hearing proceeds. Domestic violence cases are handled by Family Court Services under a separate written protocol approved by the Judicial Council, as section 3170(b) provides.

Through all of it, the judge decides. No agreement signed before marriage can take that authority away.

What a Prenup Can Address: The Financial Side of Marriage

Knowing the limit tends to bring the agreement's real purpose into focus for couples who are still drafting. Under section 1612(a), spouses-to-be may contract about:

• The rights and obligations of each of them in any property of either or both, whenever and wherever acquired or located
• The right to buy, sell, use, transfer, lease, mortgage, encumber, dispose of or otherwise manage and control property
• The disposition of property on separation, marital dissolution, death, or any other event
• The making of a will, trust or other arrangement to carry out the agreement
• The ownership rights in, and disposition of, a life insurance death benefit
• The choice of law governing the agreement's construction
• Any other matter, including their personal rights and obligations, that does not violate public policy or a statute imposing a criminal penalty

Characterizing property is the heart of most agreements. Community property is, in general terms, property acquired during marriage that belongs to both spouses; separate property belongs to one spouse alone. A prenup can say in advance which is which, and Family Code section 1500 confirms that the property rights the law would otherwise set "may be altered by a premarital agreement or other marital property agreement." Section 1610(b) defines property broadly, including income and earnings. Agreements commonly address debts as well, which fall within that last, open-ended item so long as the terms stay within public policy.

Spousal support, the support one spouse may pay the other, can also be addressed, but subdivision (c) of section 1612 attaches conditions. A spousal support provision, including a waiver, is not enforceable if the spouse it is enforced against did not have independent counsel when signing, or if the provision is unconscionable, meaning grossly unfair, at the time of enforcement. Independent counsel alone does not rescue a provision that is otherwise unenforceable.

Every item on that list concerns the two spouses. Children's rights sit outside the framework entirely.

How San Diego County Courts Handle These Issues

The Superior Court of California, County of San Diego hears family law cases in four divisions. Its ZIP Code List (ADM-254) assigns each ZIP code to one of them, and most family law cases from a given ZIP code are filed in the division it is assigned to:

• Central Division: Superior Court of California, County of San Diego, Central Courthouse, 1100 Union Street, San Diego, CA 92101
• North County Division: Superior Court of California, County of San Diego, North County Regional Center, 325 South Melrose Drive, Vista, CA 92081
• East County Division: Superior Court of California, County of San Diego, East County Regional Center, 250 East Main Street, El Cajon, CA 92020
• South County Division: Superior Court of California, County of San Diego, South County Regional Center, 500 3rd Avenue, Chula Vista, CA 91910

Whichever division hears a case, the law is the same California law. If a prenup contains a child support or custody clause and one spouse relies on it, the court looks to section 1612(b) for support and section 3011 for custody, and the clause does not control the result. A contested custody question goes to child custody recommending counseling with Family Court Services, and support is set under the statewide guideline.

The rest of the agreement, the parts about property and the other financial terms, is judged on its own, under the rules discussed in the next section.

What This Means When Drafting a Premarital Agreement

A carefully drafted prenup puts its weight where the statute allows: property, debts, and spousal support terms that meet section 1612(c). Clauses about child support or custody add nothing a court will enforce against a child's interests.

That raises a common question: does an overreaching clause about children sink the whole agreement? The statute itself does not say that it does. Section 1612(b) speaks only to the child's right to support; it does not declare the rest of the agreement void. Put simply, the clause about children falls away to the extent it would reduce that right, and whether the remaining terms still hold is a separate question. That question is answered under the enforceability rules below and under the agreement's own terms, which sometimes address what happens if one provision is not enforced.

Those enforceability rules start with the basics. Family Code section 1611 requires a premarital agreement to be in writing and signed by both parties, and section 1613 makes it effective upon marriage.

Family Code section 1615 then sets out when an agreement is not enforceable: if the party it is enforced against did not sign voluntarily, or if it was unconscionable when signed and that party lacked fair disclosure of the other's property and debts, did not waive further disclosure in writing, and could not reasonably have known about them.

The statute is specific about what "voluntary" means. Under section 1615(c), an agreement is deemed not voluntary unless the court finds, among other things, that:

• The party had independent legal counsel when signing, or, after being advised to get counsel at least seven calendar days before the final agreement was signed, waived counsel in a separate writing
• For agreements signed on or after January 1, 2020, at least seven calendar days passed between the time the party was first presented with the final agreement and the time it was signed, whether or not the party had a lawyer (section 1615(c)(2))
• An unrepresented party was fully informed, in writing and before signing, of the agreement's terms and effect and the rights being given up, was proficient in the language used, and signed a document saying who provided that information
• Nothing was signed under duress, fraud or undue influence, and both parties had capacity

In practice, the effort an agreement takes varies with what it covers: the number and kind of assets, whether spousal support is addressed, and whether both people have their own lawyers. This page covers California law only, and these are the California rules a court applies when an agreement is tested.