The Massachusetts child support calculator is Form CJD-304, a standardized worksheet the Probate and Family Court uses to produce the presumptive support amount in every case involving children. You enter each parent’s gross weekly income and a short list of allowable deductions, and the worksheet applies the state’s child support guidelines to generate a weekly figure. A judge will order that amount unless specific circumstances justify going higher or lower. The 2025 version takes effect December 1, 2025, and applies to every new order and every modification from that date forward.
Where to Get the Worksheet
The official worksheet and the full guidelines are posted on the Massachusetts Trial Court website. You can download a fillable PDF or complete the form through the court’s online portal at courtforms.jud.state.ma.us.1Mass.gov. Child Support Guidelines Paper copies are available at any Probate and Family Court. The worksheet must be filed in every case involving children, whether that’s a divorce, a paternity action, or a modification.2Mass.gov. Probate and Family Court 2025 Child Support Guidelines Worksheet CJD 304
The worksheet’s legal weight comes from two statutes. For married parents, Massachusetts General Laws Chapter 208, Section 28 directs courts to apply the guidelines and creates a rebuttable presumption that the resulting amount is correct.3General Court of Massachusetts. Massachusetts General Laws Chapter 208 Section 28 For unmarried parents, Chapter 209C, Section 9 does the same for paternity cases.4Mass.gov. Massachusetts General Laws Chapter 209C Section 9
What You Need Before You Start
The worksheet is organized into two columns, one for the payor (the parent who will pay support) and one for the recipient (the parent who primarily houses the child). Gather your documents before you sit down with it.
The central input is gross weekly income before any taxes or deductions. The guidelines define income broadly: wages and salary, tips, overtime, commissions, bonuses, Social Security benefits, pensions and retirement payments, workers’ compensation, unemployment, rental income, and investment returns all count.5Mass.gov. 2025 Child Support Guidelines Section I – Income Definition Multiple income sources all go into one gross weekly total. Recent pay stubs, tax returns, and benefit statements are the best backup.
After income, the worksheet asks for specific weekly expenses that reduce the calculation:
- Health, dental, and vision insurance premiums you actually pay. If your coverage includes people who aren’t part of the support order, the court can exclude the portion attributable to them when it would unreasonably reduce support.6Mass.gov. 2025 Child Support Guidelines Section II – Factors to Be Considered in Setting the Child Support Order
- Childcare costs that allow you to work or attend school.
- Other child support you already pay for children from a different relationship.
The numbers you enter need to match what appears on your financial statement and what you say in court. Inconsistencies cost you credibility with the judge.
How the Calculation Works
Two inputs do most of the work: the combined income of both parents and the number of children. The guidelines use a percentage-based structure in which the support obligation rises with more children, but the increase per additional child shrinks because households share fixed costs.
The worksheet takes each parent’s income, subtracts the allowable deductions, and then allocates the support obligation in proportion to each parent’s share of the combined available income. If you earn 70% of the combined total, you shoulder 70% of the obligation. The output is a weekly dollar figure, and that figure becomes the court order.
How Parenting Time Changes the Number
The amount of time each parent spends with the children significantly affects the result. The guidelines use one-third of parenting time as a key threshold. When the paying parent has the children for roughly one-third of the time or less, the standard calculation applies. When parenting time is split more evenly, the worksheet adjusts because both parents are already spending directly on the children during their own custodial time.
For arrangements where each parent has the children close to half the time, the worksheet runs the calculation in both directions and produces a support figure based on the difference between them. The higher earner typically still pays, but the amount is lower than it would be in a primary-custody case because both households carry direct costs. Judges look at the actual schedule rather than the label parents put on it.
Parenting time between the thresholds can support a deviation. The 2025 guidelines specifically identify a parent who provides “substantially more than one-third and less than one-half” of the parenting time as a circumstance that may justify an adjustment.7Mass.gov. 2025 Child Support Guidelines Section IV – Deviation
Low-Income Floor and High-Income Ceiling
The formula flexes at both ends of the income spectrum.
At the low end, the guidelines include a self-support reserve so a paying parent isn’t pushed below a basic standard of living. The court can reduce the order, and in extreme cases set it as low as zero. Whenever the guidelines would require a parent to pay 40% or more of their available income in child support, there is a rebuttable presumption that the order creates substantial hardship, which gives the judge a clear basis to reduce it.7Mass.gov. 2025 Child Support Guidelines Section IV – Deviation
At the high end, the standard formula runs up to a specified combined gross income cap. For income above that cap, the court has discretion to order additional support based on the children’s actual needs and the lifestyle they would have had if the family had stayed together. These cases become fact-intensive rather than formula-driven.
When a Judge Can Order a Different Amount
The worksheet amount is presumed correct, but it isn’t locked in. A judge can go above or below it, but to do so the court must make written findings covering three things: the amount the guidelines would have produced, why that amount would be unjust or inappropriate, and why the deviation serves the child’s best interests.7Mass.gov. 2025 Child Support Guidelines Section IV – Deviation Parents can also agree to a different number between themselves, but the judge still has to find the agreement fair and reasonable.
The 2025 guidelines list fifteen circumstances that may support a deviation. Among them:
- A child with extraordinary mental, physical, or developmental needs that carry financial consequences.
- Unusually high healthcare premiums, travel costs for parenting time, or childcare expenses.
- A child with more than two legal parents.
- A paying parent who is incarcerated with insufficient resources.
- A gross disparity in living standards that would leave one household with an unreasonably low share of the combined income.
- Child welfare involvement, where strict application might interfere with reunification efforts after a temporary removal from the home.7Mass.gov. 2025 Child Support Guidelines Section IV – Deviation
A catch-all factor allows deviation whenever the guidelines amount “would lead to an order that is unjust, inappropriate or not in the best interests of the child.” Judges have meaningful room here, but they still have to put the reasons in writing.
Attributed Income for a Parent Who Isn’t Working
A parent can’t lower a support obligation by choosing not to work or by taking a job well below their capacity. When the court finds a parent is capable of working but is unemployed or underemployed, the guidelines allow income to be “attributed,” meaning support is calculated on what that parent could earn through reasonable effort rather than what they currently take home.5Mass.gov. 2025 Child Support Guidelines Section I – Income Definition
The number isn’t invented. The guidelines direct judges to weigh education, job skills, training, work history, age, health, criminal record, and other employment barriers, along with whether jobs at that income level actually exist in the local area and whether employers would hire that parent.5Mass.gov. 2025 Child Support Guidelines Section I – Income Definition Incarceration cannot be treated as voluntary unemployment for purposes of setting or modifying support.
Changing the Order Later
A child support order stays in force until a court changes it. If circumstances shift, you have to go back to the court that entered the original order and file a modification.8Mass.gov. Learn About Changing a Child Support Order Simply paying less, or stopping altogether, invites contempt proceedings.
The common grounds for modification are:
- The current order differs from what the guidelines would produce using today’s income figures.
- A significant change in either parent’s earnings.
- Health insurance that was affordable is no longer available at a reasonable cost, or affordable coverage has become newly available.
- A change in the child’s custodial situation.8Mass.gov. Learn About Changing a Child Support Order
When you file, the judge reviews current financial statements from both parents and runs the updated numbers through the worksheet. The court then compares the new figure to the existing order and decides whether the change is significant enough to warrant a new one. A modification generally takes effect from the date you file the motion, not from the date the underlying change happened. Waiting to file costs you money you can’t recover.