Child Support Calculator Guide

The 2025 Massachusetts Child Support Guidelines took effect on December 1, 2025. There are no 2026 guidelines — the 2025 version is current. Guidelines are reviewed every 4 years.

Key changes from the 2023 Guidelines:

• Child-related expenses are now discretionary — ordering a parent to contribute toward private school, summer camps, and extracurricular activities is "discretionary and determined on a case-by-case basis" (previously required courts to consider the best interests of the children)
• Multi-parent households — for cases with more than 2 parents, courts must "consider the financial circumstances and parenting time of the legal parents to determine the most equitable result" (no specific formula given — wide judicial latitude)
• Income remains the foundation — a parent's income is the starting point of every calculation

Massachusetts uses an income-shares model. The basic idea: combine both parents' incomes, look up the recommended child support amount from the Guidelines chart, then divide it proportionally based on each parent's share of total income.

The basic steps:

1. Determine each parent's gross income — from all sources (see Section 3)
2. Subtract allowed deductions — to get each parent's net income (see Section 4)
3. Combine both parents' net incomes — this is the "combined available income"
4. Look up the Guidelines chart — find the recommended child support amount based on combined income and number of children
5. Divide proportionally — each parent's share of child support is based on their percentage of combined income
6. The Payor pays the Recipient — the parent with the higher income share (or less parenting time) pays the other. The Payor is the one who pays; the Recipient is the one who receives.

Income is broadly defined under the MA Guidelines. Include all sources:

• Wages, salary, tips, commissions — gross amount before taxes
• Self-employment income — gross receipts minus business expenses (Schedule C)
• Bonuses, overtime, severance pay
• Rental income — rent received minus expenses
• Investment income — dividends, interest, capital gains
• Pension and retirement income — including distributions from 401(k)/IRA if taken as income
• Social Security benefits — including disability (SSDI) and dependent benefits paid on behalf of the child
• Unemployment compensation
• Workers' compensation
• VA benefits
• Alimony received from a prior marriage (if applicable)
• Income from trusts — including income that can be voluntarily accessed
• Non-income-producing assets — the court can impute income if you have assets that could generate income but aren't (e.g., a vacant rental property)
• Imputed income — if you're voluntarily unemployed or underemployed, the court can assign income based on your earning capacity

From gross income, the Guidelines allow these deductions to arrive at net income:

• Federal, state, and FICA taxes — actual tax liability, not what's withheld
• Health insurance premiums — for yourself and your child(ren)
• Dental and vision insurance premiums
• Child care costs — for the child(ren) who are the subject of the support order, so the parent can work or attend school
• Child support paid — for children from other relationships (under a court order)
• Alimony paid — to a former spouse under a court order
• Mandatory retirement contributions — if required by employment

Parenting time has a major impact on child support. The Worksheet has different calculation paths depending on the custody arrangement:

Box 1: Sole Physical Custody (under 146 overnights)

If the child lives primarily with one parent (Recipient) and the other parent (Payor) has fewer than 146 overnights per year (about 40% of the time), the standard calculation applies. The Payor pays the Recipient based on the Guidelines chart.

Box 2: Shared Physical Custody (146+ overnights each)

If both parents have 146 or more overnights per year each (roughly 50/50 or close to it), the calculation changes significantly. The Worksheet computes support differently — the support obligation is reduced or eliminated based on the more equal sharing of expenses. The parent with higher income may still pay, but the amount is typically much lower than in sole custody.

Box 3: Split Custody

Different children live with different parents. Each parent is both Payor and Recipient for different children. The Worksheet calculates support for each child separately.

Box 4: Neither parent has the child(ren) most of the time

Third-party custody or the child lives with someone else. Both parents may pay support to the third party.

The official Worksheet (CJD 304) is a PDF that does the math for you if you fill it out on a computer. Here's what you'll need and how to fill it in:

What you need before you start:

• Both parents' gross annual income (from all sources listed in Section 3)
• Both parents' tax deductions (federal, state, FICA)
• Both parents' health/dental/vision insurance premiums
• Both parents' childcare costs (so parent can work/attend school)
• Number of overnights the child spends with each parent per year
• Number of children covered by this order
• Any existing child support or alimony orders you pay

Step by step:

1. Download the Worksheet: Get the 2025 CJD 304 from mass.gov. Use the interactive PDF (or the alternative fillable form if you want to save and edit later).
2. Check the correct box at the top: Box 1 (sole custody), Box 2 (shared physical custody — 146+ overnights), Box 3 (split custody), or Box 4 (neither parent primary).
3. Enter the number of children in line 1a.
4. Enter each parent's gross weekly income in lines 2a (Parent A) and 2b (Parent B). If you don't know the other parent's income, put what you believe it is.
5. Enter deductions in lines 3a–3f for each parent (taxes, health insurance, dental/vision, childcare, child support for other children, alimony paid).
6. The Worksheet calculates each parent's net income automatically (line 4) and the combined available income (line 5).
7. The Worksheet looks up the Guidelines amount based on combined income and number of children (line 6).
8. The Worksheet calculates each parent's proportional share (line 7) and the final support amount (line 8).
9. For shared physical custody (Box 2): the calculation is different — it accounts for both parents' parenting time and adjusts the support amount accordingly.
10. Add any additional expenses the court orders (childcare, health insurance, extracurricular activities — now discretionary under 2025 Guidelines).

Here's a simplified example to show how the calculation works. Actual amounts depend on the official Guidelines chart — use the Worksheet for real calculations.

Official State Resources:

• 2025 Child Support Guidelines (Mass.gov) — official page, guidelines text, worksheet, chart
• 2025 Worksheet (CJD 304) (Mass.gov) — interactive PDF + alternative fillable form
• Financial Statement Short Form (CJD 301S) — for income < $75K
• DOR Child Support Services — (800) 332-2733
• DOR Case Manager Portal — payment history, case management

Online Calculators (2025 Guidelines):

• Skylark Law 2025 Calculator — free, online, uses 2025 formula
• Cavanagh Law Calculator — includes tax impact analysis

Legal Help:

• MassLegalHelp — How to Fill Out the Worksheet — detailed plain-English instructions
• MA Legal Resource Finder — search for free/low-cost legal help
• Mass.gov — Finding Legal Help