Calculation is client-side, income figures are never transmitted or stored.
How Massachusetts Child Support Is Calculated
- Massachusetts uses WEEKLY gross income and a formula called Table A -- a piecewise (not flat) function of combined weekly income that gives the basic support amount for ONE child.
- Add both parents' weekly gross income to get combined available income, then apply Table A's formula to get the 1-child base amount.
- Multiply the 1-child amount by a fixed factor for the actual number of children: 1.40 for two, 1.68 for three, 1.85 for four, 1.94 for five (six or more reuses the five-children factor).
- Add weekly childcare and health insurance costs to get the total combined support amount, then each parent pays their share in proportion to their income.
- If the paying parent's OWN weekly income (not combined) is $391 or less, their obligation is instead calculated from Table A using their own income alone -- this is Massachusetts's Self-Support Reserve, and no add-ons apply in this zone.
- Above $8,654/week (about $450,000/year) combined available income, the result is only a presumptive MINIMUM -- courts have discretion to order more.
- This models the standard case only. It does not model the Parenting Time proportional adjustment for substantial shared parenting time, the Table C age adjustment for children 18 or older, or deductions for other children/prior support.
Massachusetts Child Support Worksheet Walkthrough
Example: Parent A earns $1,200/week gross, Parent B earns $800/week gross (combined $2,000/week). There are two children, who live primarily with Parent B.
- Combined weekly income: $1,200 + $800 = $2,000.
- Table A base for 1 child at $2,000: $346 + 18% of ($2,000 - $1,600) = $346 + $72 = $418.
- Multiply by the two-children factor: $418 x 1.40 = $585 (rounded).
- Parent A's income share: $1,200 / $2,000 = 60%.
- Parent A pays: $585 x 60% = $351/week.
How This Calculator Works — Formula & Constants
Source: Massachusetts Trial Court — Probate and Family Court, Child Support Guidelines Worksheet (CJD 304) · Calcul déterministe — no AI, no arbitrary estimate.
Constants used
| Constant | Value | Source |
|---|---|---|
| Number-of-children multiplier (Table B) | 1.00 / 1.40 / 1.68 / 1.85 / 1.94 (1-5 children) | 2025 Massachusetts Child Support Guidelines |
| Self-Support Reserve | $391/week (paying parent's own income) | 2025 Massachusetts Child Support Guidelines |
| Max combined available income | $8,654/week (~$450,000/yr) | 2025 Massachusetts Child Support Guidelines |
Formula (Table A, exact piecewise function)
combined_support = round(base_1_child × number_of_children_multiplier)
share_B = parentB_income / combined_income
obligation_B = (combined_support + add-ons) × share_B
Deterministic calculation based on Massachusetts's official Child Support Guidelines Worksheet (CJD 304). Verify against the official worksheet for a court-ready figure.
FAQ
How is child support calculated in Massachusetts?
Massachusetts uses WEEKLY gross income and a formula called Table A -- a piecewise (not flat) function of combined weekly income that gives the basic support amount for ONE child. Add both parents' weekly gross income to get combined available income, then apply Table A's formula to get the 1-child base amount. Multiply the 1-child amount by a fixed factor for the actual number of children: 1.40 for two, 1.68 for three, 1.85 for four, 1.94 for five (six or more reuses the five-children factor). Add weekly childcare and health insurance costs to get the total combined support amount, then each parent pays their share in proportion to their income. If the paying parent's OWN weekly income (not combined) is $391 or less, their obligation is instead calculated from Table A using their own income alone -- this is Massachusetts's Self-Support Reserve, and no add-ons apply in this zone. Above $8,654/week (about $450,000/year) combined available income, the result is only a presumptive MINIMUM -- courts have discretion to order more. This models the standard case only. It does not model the Parenting Time proportional adjustment for substantial shared parenting time, the Table C age adjustment for children 18 or older, or deductions for other children/prior support.
Does Massachusetts use a schedule table or a formula for child support?
A formula. Unlike most states' printed schedule tables, Massachusetts's Table A is a piecewise mathematical function of combined weekly income (different linear formulas apply across 8 income ranges) -- this calculator uses that exact formula directly, transcribed from the official worksheet's own calculation logic.
What is Massachusetts's Self-Support Reserve?
If the paying parent's own weekly gross income is $391 or less, Massachusetts calculates their obligation from Table A using their own income alone, regardless of the other parent's income, with no childcare or health insurance add-ons.
How does shared parenting time affect Massachusetts child support?
Massachusetts has a separate Parenting Time proportional adjustment (Worksheet Section 6) that can cap or adjust support when parenting time is substantially shared, comparing each parent's share of parenting time against their share of the support obligation. This calculator does not model that adjustment -- it estimates the standard case where one parent has primary care.
Methodology & Source
Formula model: ma table a shares. Effective 2025-12-01, guideline version 2025-MA-v1, last reviewed 2026-07-13.
Official source: Massachusetts Trial Court — Probate and Family Court, Child Support Guidelines Worksheet (CJD 304) (2025 Massachusetts Child Support Guidelines).
Massachusetts income figures in this calculator are WEEKLY gross income, treated as 'available income' -- it does not model the guidelines' own adjustments to available income (prior-child support paid, qualified-child deductions for other children in the home, etc.). This calculator applies the standard proportional-share calculation only. It does not model: the Parenting Time proportional adjustment (Guidelines Section II.D and Worksheet Section 6, a cap/comparison mechanism based on the recipient parent's own share of parenting time when it is substantial); the Table C age adjustment for children who are 18 or older; or cases with more than 5 children beyond reusing the 5-children multiplier as a floor. Above $450,000/yr ($8,654/week) combined available income, the guidelines state the result is only a presumptive MINIMUM, not an automatic extension -- courts have discretion to order more.
Guideline figures transcribed from the primary source above and cross-checked against Massachusetts's official calculator/worksheet for multiple test scenarios — see our verification methodology.