Child support in Massachusetts.
What the state’s own guideline says, where the number comes from, and the one figure that moves it more than anything you will argue about.
See a different stateMassachusetts
Massachusetts combines both parents' available weekly income and runs it through a worksheet built on tables A through F. The baseline assumes the children live mostly with one parent and spend about a third of the time with the other. Child care, health insurance and dental/vision costs are folded in as a combined adjustment, and the paying parent's share comes out the other end.
How Massachusetts works out the number
Authority: Massachusetts Child Support Guidelines, promulgated by the Chief Justice of the Trial Court under G.L. c. 208, § 28 (2025 Guidelines, effective December 1, 2025)The worksheet's baseline already assumes roughly one-third parenting time for the non-residential parent. Where the parents share financial responsibility and parenting time approximately equally, the worksheet itself produces a reduced order. In between: 'Where parenting time is substantially more than one-third but less than one-half for the parent who is not the residential parent, the Court may consider deviation by an adjustment to the amount calculated under the guidelines worksheet.' And in the other direction: 'Where parenting time is substantially less than one-third for the parent who is not the residential parent, the Court may consider deviation by an upward adjustment.' Massachusetts uses proportions of time, not a fixed overnight count.
Use the state’s own calculator, not ours
Massachusetts publishes this itself, free. It is called Child Support Guidelines Worksheet (CJD 304) — an interactive form on the Trial Court's own site. Findings and Determinations for Child Support and Post-Se. We are not going to build a competing calculator and ask you to trust it — this is the one a judge will recognize.
Open the Massachusetts calculator →What goes into the calculation
What counts as income
Self-employment income is 'gross receipts minus ordinary and necessary expenses required to produce income.' Overtime and second jobs get their own rule, and it cuts both ways: 'The Court may consider none, some, or all overtime income or income from a secondary job. In determining whether to disregard none, some or all income from overtime or a secondary job, due consideration must be given to the history of the income, the expectation that the income will continue to be available, the economic needs of the parties and the children, the impact of the overtime or secondary job on the parenting plan, and whether the overtime work is a requirement of the job.' And there is a presumption for new work: 'If after a child support order is entered, a payor or recipient begins to work overtime or obtains a secondary job, neither of which was worked prior to the entry of the order, there shall be a presumption that the overtime or secondary job income should not be considered in a future child support order.'
When a judge can treat you as earning more
Two distinct tools. Attribution: 'Income may be attributed where a finding has been made that a parent is capable of working and is unemployed or underemployed. Incarceration may not be treated as voluntary unemployment in establishing or modifying child support orders.' If the court finds a parent is 'earning less than they could earn through reasonable effort,' it uses earning capacity rather than actual earnings, weighing the age, number, needs and care of the children. Imputation: where reported income does not add up, the Court may 'impute income to the parent based on all the evidence submitted, including, but not limited to, evidence of the parent's ownership and maintenance of assets, and the parent's lifestyle, expenses and spending patterns.'
If you do not earn much
For a payor with gross income of $301 per week or less, 'an order of no more than $15 per week should enter.' For income between $302 and $391 per week, an order of no more than $33 per week should enter. Those cutoffs are 100% and 130% of the 2025 federal poverty guideline for a household of one. The commentary notes the $15 minimum is the old $12 minimum adjusted for inflation.
Childcare and health insurance
'Reasonable out-of-pocket child care costs actually paid after any discounts or subsidies of up to $430 per week, per child for the children covered by the child support order necessary for the gainful employment of a parent are shared by the parents in proportion to their share of combined available income.' Each parent may deduct from gross income the reasonable cost of the health care premium they actually pay, and the same for dental/vision insurance; the dental/vision cost feeds the worksheet's combined child care and health care adjustment. Health coverage is 'reasonable in cost if the cost to the party ordered to provide health care coverage does not exceed 5 percent of the gross income of the party,' and 'accessible to the child if covered services are available within 15 miles of the child's primary residence.' Private insurance is deemed not reasonably available to a parent whose gross income does not exceed 150% of the federal poverty guidelines or who receives MassHealth.
Private school, special needs, activities
Discretionary and case by case: 'Ordering the payment of other child-related expenses is discretionary and determined on a case-by-case basis. The Court shall consider whether the expenses are affordable by the parties and in the best interest of the child. Other child-related expenses may include extra-curricular activities and costs associated therewith, private school, or summer camps that do not qualify as child care.' Extraordinary medical and dental costs such as orthodontia and psychiatric counseling are treated case by case and allocated if necessary and in the child's best interest. There is a real line drawn between a camp that is child care (shareable, capped at $430/week/child) and a camp that is enrichment (discretionary), based on whether the camp exists so a parent can work or study.
When a judge can depart from the number
'There shall be a rebuttable presumption that the amount of the child support order calculated under these guidelines is the appropriate amount of child support to be ordered.' By statute, G.L. c. 208 § 28, the judge must make 'specific written findings indicating the amount of the order that would result from application of the guidelines; that the guidelines amount would be unjust or inappropriate under the circumstances; the specific facts of the case which justify departure from the guidelines; and that such departure is consistent with the best interests of the child.' A CJ-D 305 form must be completed whenever a deviation is agreed to or requested.
Two things worth knowing. First, Massachusetts has one of the broadest support windows in the country — a judge can order support to age 21 for a child living at home and dependent, and to age 23 for a child in an undergraduate program, plus a separate order to contribute to college costs capped at half the in-state UMass Amherst price. Second, the overtime rule is a genuine planning point: if you pick up overtime or a second job after your order is entered, there is a presumption that the new income should not be counted in a future order. If you took the extra work before the order, expect it to be counted.
Later on
When it ends
Not a single age. Under G.L. c. 208, § 28 the court 'may make appropriate orders of maintenance, support and education of any child who has attained age eighteen but who has not attained age twenty-one and who is domiciled in the home of a parent, and is principally dependent upon said parent for maintenance.' It may go further for a child 'who has attained age twenty-one but who has not attained age twenty-three, if such child is domiciled in the home of a parent, and is principally dependent upon said parent for maintenance due to the enrollment of such child in an educational program, excluding educational costs beyond an undergraduate degree.' A child 18 or older who is enrolled in and attending high school 'shall be deemed to be under age 18 for purposes of the guidelines and Table C, absent deviation.' For other children 18 or over, Table C reduces the guideline amount (the commentary describes a 25% reduction built into those percentages), and ordering support at all is discretionary.
College and support after 18
Yes. A Massachusetts court can order a parent to contribute to post-secondary educational expenses — 'mandatory fees, tuition, on/off campus housing, meal plan, and books' — either in addition to or instead of child support for a child 18 or older. It is not automatic: 'Contribution to post-secondary educational expenses is not presumptive.' The court weighs the cost, the child's aptitudes, where the child lives, everyone's resources including the child's, affordability including whether parents would have to spend assets or borrow, and financial aid. There is a hard ceiling: 'No parent shall be ordered to pay an amount in excess of fifty percent of the undergraduate, in-state resident costs of the University of Massachusetts-Amherst, unless the Court enters written findings that a parent has the ability to pay a higher amount.'
Changing the amount later
Massachusetts is one of the easiest states to modify in. Under G.L. c. 208 § 28, orders 'shall be modified if there is an inconsistency between the amount of the existing order and the amount that would result from application of the child support guidelines or if there is a need to provide for the health care coverage of the child.' No percentage threshold, no requirement to prove a life change. The guidelines add that a modification may also be based on health coverage becoming available, becoming unavailable, or ceasing to be at reasonable cost, or 'any other material and substantial change in circumstances.' A modification can enter 'notwithstanding an agreement of the parents that has independent legal significance.'
How far back a change can reach
We could not confirm this state’s rule on how far back an order or a change can be applied. It matters: in some states the clock starts the day you file, so filing late costs money you do not get back.
What we could not confirm
- We could not confirm from an official source how far back a Massachusetts modification reaches (usually tied to the date the other parent is served, but confirm it), or the state's official enforcement tools and interest rules. The Massachusetts Department of Revenue Child Support Services Division can answer both.
Compare all fifty states
The overnight thresholds, the ending ages and the college rules, side by side.
The rest of what we have written about Massachusetts. Every figure is quoted from Massachusetts’s own statute or its courts’ own published schedule, and carries the date we last checked it.