The short answer is no. Postnups generally cannot include child support or child custody matters. When we say “postnuptial agreement,” we’re talking about an agreement a married couple signs during the marriage with the intention of staying married. Sometimes, the term “postnuptial agreement” is used to refer to an agreement a married couple signs during a divorce. This is because the term “post” – “nuptial” simply refers to something a couple is signing after the wedding. And, if you are signing a postnuptial agreement that is incident to divorce, such as a divorce settlement agreement, then including child custody matters is fine.
With that said, let’s get into the “why” and what you are able to include in a postnuptial agreement.
Why can’t you include child support or child custody matters in a postnuptial agreement?
Virtually all states agree that including child support or child custody matters in a prenuptial or postnuptial agreement is off-limits. This is because the custody and support of a child is the right of the child, not the parents. This inquiry of how much support a child should get and whose custody they should be in should also be determined at the time of divorce. Deciding these factors, potentially years before a divorce, can have adverse outcomes for a child.
For example, let’s say a couple includes a child custody clause in their postnup that says John (the father) will have full custody of the children. Fast forward 10 years when John and Mary (the mother) are getting a divorce, and John is actually an addict at this point. He developed an addiction to drugs/alcohol and is totally unfit to have custody. However, in their postnup, it states that John has custody. As you can see, this would NOT be in the best interests of the children. A court needs to evaluate the situation at the time of the divorce to determine what is best for the children at that time.
When can you address child support or child custody matters?
You can only address child support and custody issues at the time of divorce. You can create a divorce settlement agreement that outlines a parenting plan. Often, couples come to an agreement about child matters through the mediation process. However, the court will still review and approve these matters. If you can’t come to a decision during mediation, then you will need to present your case to a court to have a judge decide based on the best interests of the child.
What can you include in a postnup?
So what can you put in a postnup if you can’t talk about children? You can put matters about property division and spousal support (in some states). There are also several other miscellaneous clauses you can include. Here are some of the things you can add to your postnup:
- Property division in a divorce
- Property ownership during the marriage
- Debt allocation
- Spousal support (in some states)
- Business ownership and division
- Contributions to joint bank accounts
- Taxes (joint filing, etc.)
- Confidentiality
- Clauses about the marital home
- Pet custody
- Mediation requirements
- Ownership of engagement rings/wedding rings
- Life insurance requirements
- Health insurance coverage
- Social media behavior
- Infidelity (in some states)
As you can see, there is a broad range of clauses that you can include, but that generally does not include child support or child custody matters. You must wait until the time of the divorce to handle those!

When is a postnuptial agreement appropriate?
A postnuptial agreement is an agreement a married couple may choose to get at any point during their marriage as long as they intend to remain married. If they want to get a divorce, they should hire a divorce attorney and consider a divorce settlement agreement. Anyone can get a postnup (as long as you aren’t planning on divorcing), but here are some couples that may especially benefit from a postnup:
Couples experiencing marital issues
If a married couple is undergoing some marital turbulence, such as infidelity or financial problems, getting a postnup can help promote marital harmony by working out certain issues and putting them on paper. This can provide peace of mind for each person and allow them to continue the marriage with the goal of improving their relationship instead of worrying about the what-ifs.
A huge change in lifestyle
For example, if a couple entered into a marriage thinking they’d never have kids and each would be independently sufficient forever, but then suddenly they have four children and one person quits their career, a postnup can help protect that person who is sacrificing their career growth to take care of the home and children.
A huge change in finances
Another reason for a postnup may be a major change in finances, such as incurring a lot of debt or receiving a lot of money. For example, if a couple enters the marriage on equal footing and then one day, one of the spouses receives a $100 million inheritance, they may want to consider a postnup.
Starting a business
If the couple or one of the spouses starts a business during the marriage, getting a postnup may be something to consider to ensure the business interests and equity remain in the possession of one person.
Estate planning
In many states, when one spouse dies, the surviving spouses can take a portion of their deceased spouse’s estate even if they were written out of the will. These laws are meant to protect spouses who were unfairly or accidentally written out of a will by a spouse. However, in a postnup, each spouse can waive their right to take this portion of the estate.
Amending your prenup
If a couple already has a prenup, they can get a postnup (a.k.a., a prenup amendment) to update any terms that have changed. However, most well-drafted prenups account for future changes. Prenup amendments would likely only be necessary for big changes or if you changed your mind on previous terms.
The bottom line on postnups and child custody and support
The takeaway is that you cannot include child custody or child support clauses in your postnup (or prenup, for that matter). It is against public policy of every state to limit or restrict the custody and support of a child in a marital agreement. Why? This isn’t the parents’ right to restrict—it is the right of the child. And this decision should be made in the child’s best interest at the time it is necessary. Typically, at the time of divorce, parents are encouraged to come to an agreement themselves (which is reviewed and approved by a judge). If they can’t reach an agreement, then they have to ask a court to step in and do an analysis of the best interests of the child.
So there you have it! Don’t include child matters in your postnup, but feel free to add in property division, spousal support, and lots of other topics! Happy planning!

Nicole Sheehey is the Head of Legal Content at HelloPrenup, and an Illinois licensed attorney. She has a wealth of knowledge and experience when it comes to prenuptial agreements. Nicole has Juris Doctor from John Marshall Law School. She has a deep understanding of the legal and financial implications of prenuptial agreements, and enjoys writing and collaborating with other attorneys on the nuances of the law. Nicole is passionate about helping couples locate the information they need when it comes to prenuptial agreements. You can reach Nicole here: Nicole@Helloprenup.com

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