New Hampshire Child Support: A Parent's Guide

In short: New Hampshire's income shares guidelines under RSA 458-C apply a percentage that scales down as income rises. A modification is available without proof after 3 years, and DHHS is required to notify parents of that right at least once every three years, with modifications taking effect from the notice date, not the eventual hearing date.

This is an educational overview written for parents, not lawyers. It isn't legal advice. For anything beyond general understanding, talk to a licensed New Hampshire family law attorney.

What New Hampshire generally provides

Under RSA 458-C, New Hampshire applies a guideline percentage to combined net income: starting at 25.6% of combined net income for one child at $15,000/year or less, gradually decreasing to 19% at combined net income of $125,000 or more, with medical support presumptively set at 4% of each parent's gross income.

Important terminology

• RSA 458-C: New Hampshire's Child Support Guidelines statute, including the modification standard at § 458-C:7.
• 3-year no-proof modification: the right to seek a modification without showing a substantial change, available three years after the last order.
• Effective from notice date: New Hampshire's rule that a modification applies from when notice was given, not from a later hearing or ruling date.

How the calculation works

A declining percentage as income rises

New Hampshire's guideline percentage starts higher for lower incomes and decreases as combined net income rises: 25.6% for one child at $15,000/year or less, down to 19% at $125,000/year or more, reflecting that higher-income families typically spend a smaller proportion of income on basic child-rearing costs. Medical support is separately set at 4% of each parent's gross income, with additional childcare and extraordinary medical costs allocated proportionally.

Requesting or defending a modification

Either parent may apply to the court or DHHS, whichever issued the existing order, for a modification 3 years after the entry of the last support order, without needing to show a substantial change of circumstances. Either party may also apply at any time based on a substantial change of circumstances. The department is required to provide notice at least once every 3 years to parties subject to an order, informing them of their right to request this review. Importantly, a granted modification is effective from the date notice was given to the respondent, not from a later hearing date, and if the modification results in an overpayment, the court must generally order reimbursement, absent undue hardship. See the child support calculator and guideline finder for jurisdiction-specific calculation sources and guidance.

How enforcement works

The Department of Child Support Services (DCSS) uses multiple enforcement tools for nonpayment, including license revocation (driver's, occupational, and professional licenses) and credit bureau reporting, alongside standard income withholding for ongoing orders.

Common questions

Do I need to show my income changed to get a modification after 3 years? No, once three years have passed since the last order, either parent can seek a modification without proving anything specific changed.

When does a new, higher (or lower) amount actually start? From the date notice of the modification was given to the other parent, not from whenever the court ultimately rules, worth knowing since it affects how far back reimbursement or additional payment might reach.

What if my co-parent isn't paying? Contact New Hampshire's Department of Child Support Services (DCSS), which can pursue license revocation and credit bureau reporting among its enforcement tools.

Practical considerations

Because a modification's effective date ties to when notice was given rather than the final ruling, keep clear records of exactly when you filed and when the other parent was notified, that date matters for calculating what's owed once the modification is granted. For the custody and parental-rights-and-responsibilities rules that intersect with this calculation, see the New Hampshire custody guide.

Official New Hampshire resources

• RSA 458-C (Child Support Guidelines)
• RSA 458-C:7 (Modification of Order)

Related OnePage resources

• Child support calculator and guideline finder
• What is a parenting plan
• Custody schedule generator

Related New Hampshire pages

• New Hampshire hub
• New Hampshire custody guide