Historical Child Support Calculator: The 2021 Massachusetts Guidelines
The Guidelines that applied from October 4, 2021 through November 30, 2025. Modification, arrears, and retroactive support arguments turn on the Guidelines in effect at the time, not the ones in effect today, so this calculator preserves that version of the worksheet.
These are not the current Guidelines. This calculator uses the 2021 Guidelines, which apply to orders entered from October 4, 2021 through November 30, 2025. They were replaced on December 1, 2025. If you are setting or modifying an order now, use the current child support calculator instead. Use this page only when the question is what an order should have been during the period this version was in effect.
Guidelines information, not legal advice. Child support in Massachusetts is governed by the Child Support Guidelines, but courts may deviate based on hardship, extraordinary circumstances, or the parties' agreement. Shared custody, self-employment income, and other complex factors require attorney review. The official worksheet produces the presumptive guideline figure, not a court order. Schedule a consultation for advice on your specific situation.
Child Support Estimator · 2021 Guidelines
This estimator follows the Massachusetts Child Support Guidelines Worksheet (CJD 304, 2021/2023 version) line by line, including Tables A, B, and C as they stood in that version. All amounts are weekly (monthly amount ÷ 4.33 = weekly).
Tables A, B and C transcribed from the official CJD 304 (2021/2023) worksheet and verified August 6, 2026.
Parent A = the parent the children primarily live with. Parent B = the other parent.
Child care costs paid (if any)
Weekly amount each parent pays per child. The 2021 Guidelines share these up to a benchmark of $355 per child per week (§II.E).
Social Security dependency benefits (uncommon)
Only if a child receives a Social Security dependency benefit because of a parent's retirement or disability.
Calculate Your Exact Figure
The Probate and Family Court used an official worksheet in every case decided under this version of the Guidelines. If you are reconstructing what an order should have been, the archived form is the document to work from.
Open the Archived 2021/2023 Worksheet (CJ-D 304)Massachusetts Trial Court form, published October 4, 2021 and last updated July 19, 2023. Opens on mass.gov. For a current order use the 2025 calculator.
What You'll Need
The worksheet asks for a handful of figures. Have these ready before you start:
- Each parent's gross weekly income, before taxes, from all sources
- The number of children covered by the order
- The parenting schedule, including the number of overnights with each parent
- Weekly cost of the children's health and dental insurance, and who pays it
- Weekly child care costs, and who pays them
Shared custody, self-employment, variable income, and combined incomes above the $400,000 cap that applied under this version can all change the result. Retroactive and arrears questions in particular reward getting the right Guidelines version onto the page.
How Massachusetts Child Support Is Calculated
Massachusetts uses an income shares model. Both parents' incomes are combined to determine what parents in that income bracket typically spend on children, and then each parent contributes their proportional share.
Combine Both Parents' Incomes
Both parents' gross weekly incomes are added together to produce the Combined Available Income (CAI). This reflects that the guidelines ask: what would these parents together spend on children if they were living in the same household?
Parent A Income
+ Parent B Income
Look Up the Basic Obligation
The Guidelines Schedule sets the Basic Child Support Obligation (BCSO) based on the CAI and the number of children. This represents the total amount both parents are expected to provide for the children's basic needs.
Schedule(CAI,
# children)
Allocate by Income Share
Each parent's share is proportional to their contribution to the CAI. Add health insurance, dental/vision, and 75% of child care costs, and then credit each parent for expenses they directly pay.
(Parent's % × Total)
− Expenses Paid
Factors That May Adjust the Guidelines Amount
Shared Physical Custody
When both parents have at least 1/3 of overnights (121+ nights/year), the guidelines apply a parenting time adjustment that typically reduces the obligation. The more equal the time, the smaller the payment.
Income Over the Cap
Under the 2021 Guidelines the maximum was $400,000 of combined available income, raised from the figure that had stood since 2009. Above that the court had discretion, though any percentage applied above the maximum was to be below the 10% applied at the top of Table A. The current Guidelines raised this cap to $450,000.
Hardship Deviations
A court may deviate from the guidelines if payment would leave the payor below the federal poverty line, if the payor supports children from another relationship, or if other extraordinary circumstances exist.
Self-Employment & Variable Income
Self-employment income is adjusted for legitimate business expenses. Bonus, commission, and other variable income may be averaged over recent years. Courts also have power to impute income to a voluntarily underemployed parent.
Child Custody in Massachusetts
Child support and custody are closely linked. Understanding how Massachusetts classifies custody arrangements helps you understand how support is calculated.
Primary Physical Custody
One parent is the primary residential parent: the child lives with them most of the time. The other parent typically has parenting time (formerly "visitation") that is less than 1/3 of overnights per year.
Shared Physical Custody
Both parents have at least 121 overnights per year (1/3 of 365). This is increasingly common in Massachusetts. The guidelines include a parenting time adjustment that reflects the increased costs for both parents when caring directly for children.
Legal Custody
Legal custody governs major decisions about the child's education, healthcare, and religion. It is separate from physical custody. Joint legal custody is the norm in Massachusetts: both parents share decision-making authority.
Split Custody
In families with multiple children, different children may primarily reside with different parents. This "split custody" arrangement involves a separate calculation for each child, with the net obligations offset against each other.