How Massachusetts Calculates Child Support
Massachusetts uses the Income Shares model to determine child support obligations. This page explains the guidelines, formula, and key factors.
Model Type
Income Shares (2025 Massachusetts Child Support Guidelines)
Massachusetts applies a tiered percentage formula (Table A) to the parents' combined weekly gross income after health and dental premiums and other support paid, scales it for the number of children and any children 18 or older, and splits it by income share. There is no overnight count: the worksheet asks whether parenting is shared, primarily with one parent (about 2/3 of the time), or split.
Sources & Verification
- Implements the 2025 guidelines effective December 1, 2025: a $450,000 combined-income cap, $15 minimum order, $301/$391 low-income tranches, $430-per-child child-care limit, and Table B factors of 1.40/1.68/1.85/1.94. Much Massachusetts material online, and many other calculators, still use the 2021 figures ($400,000, $12, $210/$249, $355).
- The arithmetic follows the official electronic worksheet (CJD 304) line for line — its embedded calculation scripts, including where it rounds to whole dollars and whole percentages — and was checked against an independent transcription of those scripts.
- The published 2025 Guidelines Chart and the worksheet's Table A formula agree at every one of the chart's 1,104 rows, but the chart skips one row at each of four column breaks on its last page (after $6,995, $7,445, $7,895 and $8,345 of weekly income). For the 49 weekly incomes in those gaps, reading the chart gives $1/week less than the formula. This calculator uses the formula, as the electronic worksheet does.
- Massachusetts has no overnight threshold. The worksheet offers three parenting plans — shared, primary residence about 2/3 of the time, and split — and parenting time substantially below 1/3 or between 1/3 and 1/2 is a discretionary deviation (§§ II.D.3-4, IV.B.8-9), so no parenting-time credit is estimated for schedules in between.
- Monthly inputs are converted to weekly (× 12 ÷ 52, the guidelines' own $450,000 ÷ 52 convention) and the weekly order back to monthly once. The weekly figure is what a Massachusetts order actually states.
- Child care is collected as each parent's monthly total plus the number of children in care, and the $430/week cap is applied assuming costs are spread evenly across those children. The worksheet applies the cap child by child, so unequal per-child costs can produce a slightly different figure.
- For split parenting plans, every child is treated as under 18: Table C's reduction for children 18 or older is applied per household on the worksheet, and which household an older child lives in isn't collected.
- Above the $450,000 cap, the amount shown is the guideline on the first $8,654/week — the minimum presumptive order. Support on the excess is at the court's discretion (§ II.C.2) and is not estimated.
- Not implemented: Social Security dependency benefits (worksheet lines 2b, 2c and 7c, including the re-run rule for shared and split plans), the hypothetical-order deduction for other children living in a parent's home (§ II.K.3, which requires a second worksheet), children with more than two legal parents (§ II.D.5), attributed or imputed income (§ I.D-E), and the 15 deviation factors in § IV.B. The 40% substantial-hardship presumption (§ IV.C) is flagged but not applied, as on the worksheet.
Income Basis & Definitions
combined weekly available gross income
Table A support for one child is adjusted for the number of children by Table B (up to five).
Source: Section II.L; Worksheet Tables A and BParent A gross income (includes most sources of income).
Source: Section I.A: Sources of incomeParenting Time Handling
The worksheet asks whether parenting is shared, primarily with one parent (about 2/3 of the time), or split. There is no overnight count.
Source: Section II.D.2; Worksheet line 1bParenting time substantially below 1/3, or between 1/3 and 1/2, is handled as a deviation rather than by formula.
Source: Sections II.D.3-4 and IV.B.8-9Deductions & Adjustments
Support actually paid under an existing order for another child or spouse is deducted from gross income; so is a hypothetical order for other children living in the home.
Source: Section II.K.1-3Alimony from someone not in the case counts as income; when alimony and child support are both at issue, the court compares running either one first.
Source: Sections I.A.19, I.A.30 and II.A.3 (Cavanagh v. Cavanagh)Add-Ons & Allocation
Out-of-pocket child care needed for work is shared by income, up to $430 per child per week.
Source: Section II.EHealth and dental/vision premiums are deducted from the paying parent's income; uninsured costs above $250 a year are divided separately.
Source: Sections II.H-JCaps, Minimums & Deviations
The guidelines apply to the first $450,000 of combined income; that amount is the minimum order and the excess is at the court's discretion.
Source: Section II.C.2Fifteen listed circumstances can justify a deviation, with written findings; an order of 40% or more of the payor's income presumes hardship.
Source: Section IV.B-C