How New Hampshire calculates child support
- Each parent’s monthly gross income is reduced by support they pay under other orders, half of any self-employment tax, mandatory retirement contributions and state income tax. The paying parent also deducts the child care and the children’s health coverage they pay.
- The state’s Guideline Calculation Table converts the parents’ combined adjusted income to net income and applies the percentage set by law for the number of children (about 19% to 26% for one child, 26% to 35.5% for two, 31% to 42.5% for three and 33.5% to 45% for four or more).
- The guideline amount is shared in proportion to income, after the receiving parent deducts the child care and health coverage they pay.
- The paying parent keeps a self-support reserve of $1,729 a month (2026): support is limited to their income above it, with a minimum order of $50.
- When parenting time is shared and the parents’ incomes are similar, the law presumes a $0 order or a deviation, so the court decides from the facts.
What the calculator asks
- How many children is the support for?
- How is parenting time split?
- Your gross income per month
- Support you pay under a court or agency order for other people
- Self-employment tax you pay per month
- Mandatory retirement contributions you pay per month
- State income tax you pay per month
- Work-related child care you pay for these children per month
- What you pay to cover these children on health insurance per month
- The other parent’s gross income per month
- Support the other parent pays under a court or agency order for other people
- Self-employment tax the other parent pays per month
- Mandatory retirement contributions the other parent pays per month
- State income tax the other parent pays per month
- Work-related child care the other parent pays for these children per month
- What the other parent pays to cover these children on health insurance per month
It never asks for names, Social Security numbers or account numbers, and your answers are not saved.
What the estimate leaves out
- Adjustments for special circumstances the court may make (RSA 458-C:5), including shared parenting schedules
- How the reasonable medical support obligation (4% of gross income) is ordered and paid
- Child support on one-time or irregular income paid when received (RSA 458-C:2, IV(c))
- Imputed income for a parent who is voluntarily unemployed or underemployed
- Combined adjusted income above the table ($31,119 a month)
When a situation is outside what the calculator covers, it says so and points you to the official worksheet instead of guessing.
Official sources
- RSA chapter 458-C, Child Support Guidelines
- 2026 Child Support Guidelines (DHHS): Guideline Calculation Table DCSS s651, Worksheet DCSS 650 and instructions
- Child Support Guidelines Worksheet, DCSS 650 (04/26)
- State of New Hampshire Child Support Calculator (amounts effective April 1, 2026)
New Hampshire Child Support Guidelines Worksheet (DCSS 650) →
Ready to estimate? The calculator shows each worksheet line so you can check it against the official form.
Open the New Hampshire calculator →An estimate from the published guideline formula, not a prediction of a court order. The official court worksheet and the court’s decision control. General information, not legal advice. LawCat is not a law firm.