New Hampshire Child Support — Calculator, Laws & Guide (2026)

Understanding New Hampshire child support laws helps both custodial and non-custodial parents know their rights and obligations. This comprehensive New Hampshire child support guide covers how payments are calculated, what income counts, when support can be modified, and how orders are enforced. Whether you are going through a divorce, seeking a modification, or dealing with non-payment, this guide explains New Hampshire’s child support system in plain language.

Verified against New Hampshire statutes and federal OCSE guidelines as of May 2026.

New Hampshire Child Support Overview

New Hampshire uses the income shares model for calculating child support. This model is based on the principle that children should receive the same proportion of parental income they would have received if the family were intact. Both parents’ incomes are combined, and the support obligation is divided proportionally.

New Hampshire uses the income shares model under RSA 458-C. Both parents’ adjusted gross incomes are combined, then guideline percentages are applied to combined net income based on the number of children: approximately 25% for one child, 33% for two children, 40% for three children, and 45% for four or more children. The total obligation is then divided proportionally between parents based on each parent’s share of combined income. As of January 1, 2025 (HB 1564), if parents have approximately equal parenting time (each parent >40%) and substantially similar incomes (within 10% difference), there is a rebuttable presumption that neither parent owes child support. A substantially shared parenting schedule (each parent >35%) may also result in a deviation from guidelines.

How New Hampshire Calculates Child Support

The New Hampshire child support calculation considers multiple factors:

1. Determine each parent’s gross income — wages, salary, commissions, bonuses, self-employment income, investment income, and other sources.
2. Calculate combined parental income — add both parents’ adjusted gross incomes together.
3. Apply the guideline schedule — New Hampshire’s guidelines provide a base support amount based on combined income and number of children.
4. Prorate between parents — each parent’s share is proportional to their percentage of the combined income.
5. Add healthcare and childcare costs — these are added to the base amount and divided proportionally.
6. Apply adjustments — parenting time credits, other child obligations, and special circumstances may adjust the final amount.

Online calculator: Use our child support estimator below to calculate your estimated obligation.

What Counts as Income in New Hampshire

Gross income from all sources, whether earned or unearned, including but not limited to: wages, salary, commissions, tips, annuities, social security benefits, trust income, lottery or gambling winnings, interest, dividends, investment income, net rental income, self-employment income, alimony, business profits, pensions, bonuses, and government program payments including workers’ compensation, veterans’ benefits, unemployment benefits, and disability benefits. The income of a parent’s current spouse is not counted as gross income unless the parent is voluntarily unemployed or underemployed, in which case the spouse’s income may be imputed to the extent the parent had previously earned income. Net income is calculated by deducting federal taxes and FICA/Medicare from gross income using IRS Publication 15-T withholding tables for a single person claiming two allowances.

Imputed income: YES. The court may consider as gross income the difference between what a parent currently earns and what they have previously earned if the parent voluntarily becomes unemployed or underemployed, unless the parent is physically or mentally incapacitated. Incarceration is specifically excluded from being considered voluntary unemployment. The court has discretion and may choose not to impute income when a parent returns to school to increase future earning potential or stays home to care for a young child. If the parent is voluntarily unemployed, the court may impute income from the current spouse to the extent the parent previously earned. Even if unemployed, the minimum support order is 50 per month.

Deviation factors: Under RSA 458-C:5, the court may deviate from guidelines when special circumstances exist, including: (a) ongoing extraordinary medical, dental, or education expenses, including expenses related to special needs of a child; (b) significantly high or low income of either parent; (c) economic consequences of the presence of stepparents, stepchildren, or other natural or adopted children; (d) reasonable expenses incurred by the obligor in exercising parental rights and responsibilities, provided the obligee’s reasonable expenses for the children can still be met; (e) economic consequences of providing for voluntary or court-ordered postsecondary educational expenses of a natural or adopted child; (f) other special circumstances to avoid an unreasonably low or confiscatory support order. The party seeking a deviation must prove special circumstances by a preponderance of the evidence. The court must make written findings explaining any deviation. Approximately equal parenting time (>40% each parent) or substantially shared parenting time (>35% each parent) may also result in adjustments under the 2025 amendments.

Healthcare & Childcare in New Hampshire Child Support

Health insurance: The obligor’s reasonable medical support obligation is calculated by multiplying the obligor’s monthly gross income by 0.04 (4%) and rounding to the nearest whole dollar. Health insurance premium costs for the children are factored into the support calculation. Additional costs for health insurance beyond the medical support amount, as well as uninsured extraordinary medical expenses, are allocated between parents in proportion to their respective shares of combined income. Courts may order either parent to maintain health insurance coverage for the children.

Childcare costs: Childcare costs necessary for employment, job search, or education/training of the custodial parent are added to the basic child support obligation. These costs are allocated between the parents in proportion to their respective shares of combined adjusted gross income, similar to how health insurance costs are divided.

When Does New Hampshire Child Support End?

In New Hampshire, child support generally ends when the child reaches Child support terminates when the child reaches age 18 or completes high school, whichever is later, or upon the child’s marriage, enlistment in the armed services, or emancipation — whichever occurs first. No further legal action is required for termination. For children with disabilities, support orders effective after July 9, 2013 may continue until the child reaches age 21 or no longer qualifies as a child with a disability.. However, support may continue or end earlier based on:

• The child graduates from high school (if still a minor)
• The child becomes emancipated (marriage, military service, self-supporting)
• The child has special needs requiring ongoing support
• College support: NO. Under RSA 461-A:14(V), no child support order may require a parent to contribute to an adult child’s college or postsecondary education expenses beyond completion of high school. However, under RSA 461-A:21, parents may voluntarily agree in a stipulated decree (signed by both parents and approved by the court) to contribute to college expenses. Such agreements are enforceable by the court and may specify amounts, percentages, or formulas for contributions. This is a voluntary agreement only — courts cannot order it.

Modifying New Hampshire Child Support

When to modify: Either parent may apply to modify a child support order every 3 years from the date of the last order without needing to show a substantial change of circumstances. At any other time, a modification requires proof of a substantial change of circumstances that makes the original order unfair, such as: significant change in either parent’s income or employment status, changes in the needs of the child, changes in custody or parenting time, or termination of support for one of multiple children (which is specifically defined as a substantial change). Additionally, the 2025 law changes regarding shared parenting time may trigger modifications for existing orders.

How to modify: A parent may file a Petition to Change Court Order along with a Personal Data Sheet and a Child Support Guidelines Worksheet with the Family Division of the New Hampshire Circuit Court. Alternatively, either parent can apply to the Bureau of Child Support Services (BCSS) within NH DHHS, which can initiate a review and adjustment of the child support order. The modification is not effective prior to the date that notice of the petition is served on the other parent.

Either parent can request a modification. Changes are typically not retroactive to before the date of filing the modification request.

New Hampshire Child Support Enforcement

New Hampshire has multiple tools to enforce child support orders when a parent fails to pay:

• Income withholding/wage garnishment (employer must implement within 14 days of notice; maximum 60% of net pay if supporting a second family
• 65% if not); federal and state tax refund intercept; passport denial (when arrears exceed 2500); liens against personal and real property; lottery prize intercept; credit bureau reporting of arrears amounts; suspension of driver’s license
• recreational licenses
• and professional licenses; contempt of court proceedings (show cause hearings where obligor must explain failure to pay
• penalties include fines
• jail time
• and payment of other party’s attorney fees); criminal non-support prosecution (can result in incarceration)

Contact Division of Child Support Services (DCSS), also known as Bureau of Child Support Services (BCSS), within the New Hampshire Department of Health and Human Services (DHHS) at https://www.dhhs.nh.gov/programs-services/childcare-parenting-childbirth/child-support-services/child-support-enforcement for enforcement assistance.

Additional New Hampshire rules: Minimum support order of 50 per month even if obligor is unemployed. Self-support reserve set at 130% of federal poverty guideline (increased from 115% effective January 1, 2025 under HB 1564). Medical support is calculated as 4% of obligor’s gross monthly income. New Hampshire has no state income tax, which affects net income calculations. The 2025 amendments created specific definitions for approximately equal parenting time (>40% each parent) and substantially shared parenting time (>35% each parent), with a rebuttable presumption of no support when parents have approximately equal time and substantially similar incomes (within 10% difference). The guideline table uses combined monthly adjusted gross income in 10-dollar ranges with interpolated percentages between income levels.

Official Sources & Resources

• Division of Child Support Services (DCSS), also known as Bureau of Child Support Services (BCSS), within the New Hampshire Department of Health and Human Services (DHHS): https://www.dhhs.nh.gov/programs-services/childcare-parenting-childbirth/child-support-services/child-support-enforcement
• Federal OCSE: acf.hhs.gov/css
• Cornell LII — Child Support: law.cornell.edu
• New Hampshire Guidelines Statute: RSA Chapter 458-C (New Hampshire Revised Statutes Annotated, Title XLIII, Chapter 458-C: Child Support Guidelines)

Last verified May 2026. Contact us if you notice outdated information.

Estimate Your Child Support

Use our free child support estimator to calculate estimated monthly payments. Enter both parents’ incomes, number of children, and custody arrangement to see a personalized breakdown based on your state’s formula.

Related Guides

• New Hampshire Divorce Process Guide
• New Hampshire Child Custody Guide
• New Hampshire Alimony Guide
• All Child Support Guides