Every now and then, we see the same story play out in New Hampshire family courts. Two parents separate. A court order is put in place: Parent A has primary residential responsibility, Parent B pays child support. That seems straightforward enough.
Then life happens. Maybe Parent A takes a new job out of state. Maybe Parent B has more stability. Whatever the reason, the parents agree between themselves that Parent B will now have the kids most of the time. The problem? They don’t go back to court to make it official. Parent B stops paying child support, since the kids live with them now. On paper, though, the old order is still in effect. Month after month, the unpaid support piles up. Suddenly, Parent B has what looks like a massive arrearage, even though in reality they were the one feeding, clothing, and housing the child.
This is one of those situations where real life and the legal system don’t always line up. And unfortunately, New Hampshire law doesn’t provide an easy “reset” button. Let’s break down why this happens, and what can be done.
Arrearages Are Locked In
Under New Hampshire law, once a child support payment comes due, it becomes a judgment. That means it’s locked in and owed, regardless of later changes in circumstances. The statute, RSA 461-A:14, is very clear: courts cannot go back and erase arrears that have already built up.
This rule is based on a policy choice. The state doesn’t want parents informally bargaining away financial support that’s meant for children. So the law is intentionally rigid. But that rigidity creates “phantom arrearages.” On paper, Parent B owes thousands. In reality, they were the one providing support.
What the Court Can Actually Do
So what happens if Parent B ends up in front of a judge years later? There are a few possible outcomes, none of them automatic.
1. Prospective modification.
The cleanest fix is to file for a modification as soon as residential responsibility shifts. Either parent can do this under RSA 458-C:7. The court then issues a new order, adjusting child support going forward. But here’s the rub: many parents never file. They just adjust informally, and the paperwork never catches up.
2. Equitable defenses.
New Hampshire courts have sometimes recognized defenses like estoppel or laches when enforcing arrears would be deeply unfair. For example, if Parent A allowed Parent B to raise the child without support for years, and then suddenly demanded back payments, a judge might say no. But this isn’t guaranteed. Each case turns on its facts, and judges have broad discretion.
3. Credit for actual support.
Courts sometimes give credit against arrears for expenses Parent B actually paid while the child lived with them. That might include groceries, school costs, or housing. But again, it requires proof and a formal request. The credit may or may not wipe out the entire arrearage.
Practical Options for Parents
If you ever find yourself in this type of role-reversal situation, what should you do?
File to modify immediately. Even if you and your ex are on great terms, don’t rely on a handshake deal. A quick filing can save years of headaches.
Document everything. Keep records of expenses, receipts, and proof that the child has been living with you. If arrears become an issue, this documentation will help.
Negotiate a settlement. Sometimes the other parent is willing to agree not to pursue collection, especially if they know you were covering the child’s needs. If the state is not involved, this can resolve things privately.
Ask for equitable adjustment. If arrears enforcement starts, Parent B can file a motion asking the court to credit the support they actually provided. Some judges are receptive, others are stricter. But it’s better to raise the issue than to let arrears snowball unchecked.
Why There’s No Easy Button
Parents often ask: why can’t the court just wipe the slate clean? The answer comes down to policy. The law values stability and enforceability in child support. If private side agreements were enough to undo orders, children’s financial security could be undermined. The rigidity may feel unfair in individual cases, but it’s meant to prevent abuse.
That said, judges do recognize reality. If a child has lived with Parent B for years, most courts will at least consider giving credit or limiting enforcement. It’s just not automatic, and it often takes legal filings and hearings to sort out.
This residential responsibility-flip scenario is surprisingly common. And every time, it highlights the gap between what families do informally and what the law requires formally. In New Hampshire, once arrears are on the books, they can’t simply be erased. But there are tools parents can use: filing for modification, raising equitable defenses, and seeking credit for actual support.
The takeaway is simple: don’t wait. If residential responsibility changes, file right away. A little paperwork now can prevent years of legal and financial headaches down the road. And if you’re already stuck in the arrearage trap, know that there are still arguments you can make. It may not be a perfect fix, but courts do have some flexibility to make sure the outcome is fair.
Residential Responsibility Flips but Child Support Orders Don’t