Leaving a Marriage for a New Partner: Effects on the Kids

It's late, the kids are asleep down the hall, and you're rehearsing how to tell them, and wondering what this will do to them. No article can predict how your own child will take it. But the parts that shape their lives most are largely in your hands or set by clear rules. A court will decide where they live based on their best interests. Child support has firm rules. When and how they meet your new partner is your call. Whether the affair counts legally depends on your state.

You're Not the Only Family Doing This

Divorce is common, even if it doesn't feel that way from inside your own house. Provisional federal figures count 662,950 divorces and annulments in 2024, a rate of 2.3 per 1,000 people. That is down slightly from 672,502 in 2023. Those totals are incomplete, because several states, including California, don't report their divorce counts to the national system. The real number is higher. Many of those families had children at home, and they faced the same questions you're facing.

The Question a Court Asks: What's Best for the Child

If you and your spouse can't agree on custody, a judge will decide. The standard is the same across the country. Every state, plus D.C. and the territories, has a law requiring courts to consider the child's best interests in custody decisions.

What "best interests" means in practice varies by state. California's Family Code makes the child's health, safety and welfare the primary concern. Connecticut's list includes the child's age, relationships and needs. Some states weigh a child's reasonable preference in certain decisions. How much a child's wishes count, how abuse history is handled, and which factors come first all depend on your state's statute, not on one national rule. Read your own state's law, or ask a family lawyer to walk you through it.

Does Leaving for Someone Else Change the Case?

It might, and again it depends on where you live. In some states, fault matters mostly for money. Virginia generally bars a spouse who committed adultery from receiving spousal support unless denying it would be a "manifest injustice." North Carolina can bar a dependent spouse who committed adultery from receiving alimony. These rules are worth confirming in the current statutes with a local attorney.

Other states care much less about fault. In California, a community property state, marital assets are generally split 50/50 no matter who cheated. One thing can hurt you in many places: spending marital money on a new partner. Some states can order the spending spouse to pay that money back to the marriage. If you've been paying for dinners, trips or gifts out of joint funds, expect that to come up.

For your children, the practical point is this. A contested fight over fault drags the process out, and children usually live through that fight. Knowing your state's rules early helps you decide which battles are worth having.

The Money Your Children Depend On: Child Support

Child support is the piece of the divorce built entirely around the kids, and its tax treatment is simple. The IRS says child support is never deductible for the parent who pays it and isn't counted as income for the parent who receives it.

One rule catches people off guard. If one parent owes both child support and alimony and pays less than the full amount, the IRS treats the money as child support first. Only what's left over counts as alimony.

To set up, change or enforce a support order, start with your state's child support agency. These agencies work under the federal Office of Child Support Services. That office was formerly called the Office of Child Support Enforcement and was renamed under a rule that took effect March 3, 2025. Older paperwork and websites may still use the old name.

Alimony Works Differently Than It Used To

A lot of advice still claims that alimony is deductible for the payer and taxable for the recipient. For newer divorces, that is wrong.

• Agreements signed after 2018: The payer can't deduct alimony, and the recipient doesn't report it as income.
• Agreements signed before 2019: The old rule generally still applies. The payer deducts the payments and the recipient reports them as income.
• Older agreements that are later modified: They keep the old treatment unless the modification expressly says the new rule applies.

This affects your children indirectly. Under current rules, alimony costs the paying parent more after taxes than it once did, and that can change how much is left for the kids' needs in each household.

Timing the Decree Changes Your Tax Return

For federal taxes, your marital status is set on the last day of the year. If your final decree of divorce or separate maintenance arrives by December 31, you're treated as unmarried for that entire year. If you're separated but don't have a final decree yet, you're still treated as married. When your case wraps up can change which filing status you can use, so plan with a tax preparer if the decision falls near year-end.

Splitting Retirement Accounts Without an Avoidable Tax Bill

Retirement savings are often the largest asset after the house. They're also where you can lose money that would otherwise go toward your children's future.

• 401(k)s and pensions are divided with a qualified domestic relations order, or QDRO. A payout to the former spouse under a QDRO is generally exempt from the 10% early-withdrawal penalty. The account owner's own early withdrawals are not exempt.
• IRAs don't use QDROs. They're split by a "transfer incident to divorce," either as a direct transfer between custodians or by retitling the account. If you withdraw cash and hand it to your ex, that counts as a taxable withdrawal.

Confirm the details with the plan administrator and a tax professional before anything moves.

Be wary of the claim that the spouse who leaves forfeits their share of retirement benefits. State property law controls how marital retirement savings are divided. Don't assume your choice to leave costs you your share, and don't assume it can't. Get advice for your state.

Telling Your Kids, and Introducing Someone New

This is the part no court controls. The American Academy of Pediatrics' guidance on dating after divorce suggests the following for school-age children:

• Give them a clear explanation of your feelings.
• Explain how adult relationships differ from their own friendships.
• Invite them to say what they feel, good or bad.
• Let them ask questions about the new person.

The rest is judgment. In my opinion, a few principles are worth holding to, though none of them come from a rule or a study:

• Don't ask your children to keep secrets from their other parent.
• Don't make the new partner the topic of the first conversation about the divorce.
• Wait to introduce someone until you're confident they'll still be around.

Your children have to absorb two changes: losing the family as they knew it, and gaining a stranger. Giving them time between the two is a kindness.

Where That Leaves You

If you're leaving for a new partner, your children feel the effects through a few channels. A best-interests custody decision governed by your state. Child support with clear, stable rules. Alimony and tax rules that changed after 2018. Retirement splits that can be done cleanly or expensively. And the conversations you have at home. Learn your state's rules, settle what you can without a fight, and let your kids meet the new person in your life only after the old one has had a chance to end well.

Sources (11)

• IRS, Topic 452, Alimony and Separate Maintenance: irs.gov
• IRS, Publication 504, Divorced or Separated Individuals: irs.gov
• CDC/NCHS, Provisional number of marriages and divorces, 2000–2024: cdc.gov
• CDC/NCHS, FastStats: Marriage and Divorce: cdc.gov
• Child Welfare Information Gateway, Determining the Best Interests of the Child: childwelfare.gov
• Administration for Children and Families, Office of Child Support Services: acf.gov
• Bryan Fagan Law, Comparing Adultery Laws in Texas to Other States: bryanfagan.com
• Berenji Family Law, adultery and divorce in California: berenjifamilylaw.com
• Mezzi, Gray Divorce and QDROs: mezzi.com
• FileTax, Divorce and Retirement Accounts: filetax.com
• HealthyChildren.org (American Academy of Pediatrics), Adjusting to Divorce: healthychildren.org