Child Support in Massachusetts: Guidelines and Calculations

A father in Worcester earning $110,000 per year ran the numbers on Massachusetts’s child support calculator expecting a payment around $300 per week. The actual guidelines worksheet produced an obligation closer to $400. His reaction — “That can’t be right” — is one family law attorneys in Massachusetts hear constantly. Massachusetts consistently produces some of the highest child support obligations in the country, and the formula behind the numbers is more nuanced than most parents realize.

The state’s 2025 Child Support Guidelines, effective December 1, 2025, brought meaningful changes to income thresholds, childcare cost caps, low-income protections, and the way courts handle the intersection of alimony and child support. Whether you’re going through a divorce, establishing paternity, or revisiting an existing order, understanding how these guidelines work gives you a clearer picture of what to expect. For a national overview, see our guide on how child support is calculated, and try our child support calculator for a quick estimate.

How Massachusetts Calculates Child Support

Massachusetts uses the income shares model, the same framework adopted by roughly 40 states. The core principle: a child should receive the same share of parental income they would have received if the family stayed together. Instead of basing support on one parent’s income alone, the model combines both parents’ incomes to determine the total support obligation, then divides that obligation proportionally.

Here’s how the calculation works at a high level:

1. Determine each parent’s weekly gross income
2. Subtract certain costs from each parent’s income — health insurance for the child, childcare, and support paid for other children
3. Combine both parents’ adjusted incomes
4. Look up the base child support amount on Table A of the guidelines worksheet, based on combined income and the number of children
5. Calculate each parent’s percentage share of the combined income
6. Apply a parenting time adjustment based on the custody arrangement
7. The parent without primary custody (or with less parenting time) typically pays the resulting amount to the other parent

The guidelines treat this calculated amount as presumptively correct. A court must order the guidelines amount unless a parent demonstrates — with evidence — that the amount would be unjust or inappropriate. If the court deviates, it must explain why in written findings.

What Counts as Income

The Massachusetts guidelines define gross income broadly. For child support purposes, income means gross income from whatever source, regardless of whether that income is recognized by the IRS or reported to any taxing authority.

Gross income includes:

• Salaries, wages, overtime, tips, and commissions
• Self-employment income (gross receipts minus ordinary and necessary business expenses)
• Severance pay
• Pensions, annuities, and Social Security benefits
• Unemployment compensation and workers’ compensation
• Disability insurance benefits
• Veterans’ benefits (except means-tested benefits)
• Military pay and allowances
• Investment income — interest, dividends, capital gains
• Trust income and annuities
• Rental income
• Royalties, patents, and copyrights
• Alimony received from the current or any prior relationship
• Digital assets and other nontraditional forms of compensation (expressly added in the 2025 guidelines)

Items excluded from gross income:

• Means-tested public assistance (TAFDC, SNAP, SSI)
• Income earned by a new spouse or domestic partner (though it may be relevant in deviation analysis)
• Child support received for children of a different relationship

Imputed Income

If a parent is voluntarily unemployed or underemployed, the court may impute income — assign an earning capacity based on what the parent could reasonably earn. The court looks at education, training, work experience, and available jobs in the local market.

The 2025 guidelines go further when a parent has unreported or undocumented income. The court can impute income based on all available evidence, including the parent’s ownership of assets, lifestyle, and spending patterns. If the court finds unreported income, it may also adjust the imputed amount upward to account for the absence of income taxes that would normally apply.

Self-Employment Income

For self-employed parents, the court examines whether claimed business deductions are genuinely reasonable and necessary to produce income — without regard to whether those deductions are allowable for tax purposes. A parent who runs $30,000 in personal expenses through a business will see those amounts added back into the income calculation.

The Child Support Guidelines Worksheet

The guidelines include an official worksheet that parents, attorneys, and judges use to calculate the presumptive support amount. Massachusetts calculates child support on a weekly basis.

Step-by-step process

1. Enter each parent’s weekly gross income. Convert annual salary by dividing by 52.
2. Subtract qualifying costs from each parent’s gross income:
   • Health insurance premiums for the child (the child’s share only, not the parent’s coverage)
   • Dental and vision insurance for the child
   • Work-related childcare costs (up to $430 per child per week under the 2025 guidelines)
   • Child support paid for children from other relationships
3. Combine both parents’ adjusted incomes to get the combined available income.
4. Look up the base support amount on Table A using the combined income and the number of children. Table A uses marginal percentages that start at 22% of the lowest income levels ($250-$750/week combined) and decline to 10% at the highest combined income levels.
5. Divide the support obligation proportionally based on each parent’s share of the combined income.
6. Apply the parenting time adjustment depending on the custody schedule.

Income cap

The 2025 guidelines provide presumptive support amounts for combined gross incomes up to $450,000 per year — an increase from the $400,000 cap under the 2023 guidelines. For incomes above this threshold, the court has discretion to set support based on the child’s needs and the standard of living the child would have enjoyed if the family remained together.

Low-Income Protections and the Minimum Order

The 2025 guidelines built stronger protections for low-income payors, recognizing that the prior minimum order of $25 per week left some parents without enough to cover basic living costs.

The current structure:

The guidelines also set a minimum subsistence level of $391 per week. If paying the presumptive child support amount would push a payor’s income below this threshold, the court may consider a deviation.

There’s also a broader safeguard: a rebuttable presumption of substantial hardship exists whenever the total child support obligation exceeds 40% of the payor’s available income. That 40% threshold falls between economic estimates of child-rearing costs for one and two children, meaning support obligations above it are presumed to create genuine financial hardship that warrants court review.

Parenting Time Adjustments

The Massachusetts guidelines factor in how much time each parent spends with the child, since a parent who has the child more often incurs direct costs for food, housing, transportation, and activities.

Under the 2025 guidelines, the same worksheet handles all custody arrangements:

• Approximately two-thirds / one-third — the standard arrangement where one parent has the child roughly two-thirds of the time
• Shared parenting (close to 50/50) — a more significant adjustment applies, though support is not eliminated when there is an income disparity between parents
• Split custody — where each parent has primary custody of at least one child

When the non-residential parent’s parenting time is substantially less than one-third, the court may consider an upward deviation. When parenting time is substantially more than one-third but less than one-half, the court may adjust the amount calculated under the worksheet.

Equal custody does not mean zero child support. If one parent earns $120,000 and the other earns $60,000, the higher-earning parent will still pay support to equalize the child’s standard of living in both homes. For more on this dynamic, see our guide on child support with 50/50 custody.

Healthcare and Childcare Costs

Health insurance

The cost of providing health insurance for the child is factored into the guidelines calculation. The child’s share of the premium (not the parent’s own coverage cost) is subtracted from the insuring parent’s gross income before calculating support. This effectively divides the insurance cost proportionally between both parents.

Uninsured medical expenses

The parent receiving child support pays the first $250 of out-of-pocket uninsured medical, dental, and vision expenses each year. Beyond that $250 threshold, the 2025 guidelines changed how additional costs are shared. Courts may now consider each parent’s percentage of combined available income when allocating uninsured expenses — a shift from the older practice of simply splitting costs 50/50.

Childcare costs

Work-related childcare — daycare, after-school programs, summer camps — is treated separately in the calculation. Reasonable out-of-pocket childcare costs up to $430 per child per week are factored into the worksheet. That $430 cap represents a significant increase from the $355 cap in the 2023 guidelines, reflecting a 26% increase in Massachusetts childcare costs since 2021.

The 2025 guidelines clarify two points about childcare costs:

• Only costs paid out-of-pocket by a parent count — subsidies or payments by third parties are excluded
• Summer camp or activity costs qualify as childcare when the court evaluates the need for and purposes of the services, the age of the children, the time during which services are provided, and the nature of the services

When the Court Deviates from the Guidelines

The guidelines amount is presumptively correct, but courts can deviate when applying it would be unjust or inappropriate. The parent seeking a deviation bears the burden of proof, and the court must issue written findings explaining any deviation.

Factors courts consider when deciding whether to deviate:

• Extraordinary medical, dental, or educational expenses for the child
• The child’s own financial resources (trust funds, inheritance, independent income)
• The standard of living the child would have enjoyed if the family remained intact
• Income of a new spouse or partner (while excluded from the base calculation, it can support a deviation)
• Extraordinary travel expenses for parenting time
• Existing child support obligations for other children
• Tax consequences of the support arrangement
• The parties’ agreement (if both parents agree to deviate and the child’s needs are met)
• Parenting time significantly more or less than one-third for the non-residential parent
• More than two legal parents — the 2025 guidelines add a new deviation provision for children with more than two legal parents under the amended G.L. c. 209C

The 40% hardship rule applies here: when the total support obligation exceeds 40% of the payor’s available income, there is a rebuttable presumption of substantial hardship justifying a deviation.

How Child Support and Alimony Interact

When both child support and alimony are at issue in a case, the 2025 guidelines formalize a structured approach based on the Massachusetts Supreme Judicial Court’s decision in Cavanagh v. Cavanagh.

The framework requires courts to:

1. Calculate alimony first based on the parties’ total gross incomes — including income above the $450,000 child support cap
2. Adjust each parent’s income by subtracting alimony paid (for the payor) and adding alimony received (for the recipient)
3. Calculate child support second using the adjusted, post-alimony incomes

This matters because the order of operations affects both amounts. Alimony paid reduces the payor’s income for child support purposes, which lowers the child support obligation. Alimony received increases the recipient’s income, which also changes the proportional split.

The guidelines also require courts to consider the reverse calculation — child support first, then alimony on income not already used for support — and enter the order that produces the most equitable result.

College Costs: Support for Children Ages 18 to 23

Massachusetts is one of a limited number of states where courts can order parents to pay for a child’s college education. Under MGL Chapter 208, Section 28, the court’s authority extends beyond the child’s 18th birthday.

Ages 18 to 21

The court may order support for a child who is domiciled in the home of a parent and principally dependent on that parent for maintenance. The child does not need to be enrolled in college — this applies generally.

Ages 21 to 23

The court may order support for a child in the same circumstances, but with an additional requirement: the child must be enrolled in an educational program. The statute excludes costs beyond an undergraduate degree — graduate school is not covered.

The UMass cost cap

Under the guidelines, no parent can be ordered to pay more than 50% of the in-state undergraduate cost of attending the University of Massachusetts-Amherst, unless the court makes written findings that a parent has the ability to pay more. That benchmark uses published tuition, mandatory fees, and room and board as reported in the College Board’s Annual Survey of Colleges.

Key details about college support

• A child living on campus can still be considered “primarily domiciled” with a parent
• The court considers each parent’s financial ability and the child’s own resources (scholarships, financial aid, part-time earnings)
• Parents can address college costs proactively in their separation agreement
• The obligation is discretionary — the court is not required to order college support

How to Modify a Child Support Order

Child support orders in Massachusetts are not permanent. Either parent can request a modification when circumstances have materially changed.

Grounds for modification

A parent must show a material and substantial change in circumstances since the last order. Common qualifying changes include:

• Significant increase or decrease in either parent’s income
• Job loss or involuntary reduction in hours
• A change in the child’s needs (new medical or educational expenses)
• A change in the parenting time arrangement
• Updated guidelines that produce a meaningfully different amount from the current order

That last point matters: when the guidelines are revised (as they were in December 2025), an existing order that differs significantly from the new guidelines amount can itself constitute a material change in circumstances — even if neither parent’s financial situation has changed.

Filing the complaint

To modify child support, file a Complaint for Modification (form CJD 104) with the Probate and Family Court that issued the original order. The costs:

• Filing fee: $50
• Summons fee: $5
• Service costs: $35-$45 (paid to a deputy sheriff or constable)

If you cannot afford these fees, you can request a fee waiver by filing an Affidavit of Indigency.

When the modification takes effect

Modifications are effective from the date the complaint is filed, not retroactively. Support arrears that accrued before the filing date are not reduced. If your circumstances change, file promptly — delays cost money.

For more on the modification process nationally, see our guide on modifying child support.

Enforcement

When a parent falls behind on child support payments, Massachusetts provides strong enforcement tools through the Department of Revenue, Child Support Enforcement Division (DOR/CSE).

Available enforcement actions include:

• Income withholding (wage garnishment) — the most common method; federal rules cap withholding at 25% of weekly disposable income
• Tax refund interception — both state and federal refunds can be redirected to cover arrears
• License suspension — driver’s licenses, professional licenses, and recreational licenses (hunting, fishing) can all be suspended with no hardship exceptions
• Credit bureau reporting — overdue support is reported to credit agencies
• Bank account seizure — funds can be levied directly from bank accounts
• Contempt of court — willful failure to pay can result in fines and incarceration

If you are owed support and not receiving it, contact the DOR/CSE or learn more in our guide on child support enforcement.

What to Do Next

1. Gather your financial documents. The calculation starts with accurate income information. Collect recent tax returns, pay stubs, W-2s, 1099s, and records of self-employment income, investment income, and any other income sources.
2. Run the numbers. Use the official Massachusetts child support guidelines worksheet or our child support calculator for an estimate based on the current guidelines.
3. Understand your parenting time. The custody arrangement directly affects the support amount. Have a clear picture of the actual or proposed parenting schedule.
4. Account for healthcare and childcare. These costs are factored separately and can significantly change the final number. Know what you’re paying and what the child needs.
5. Talk to a family law attorney. Massachusetts child support involves multiple variables — income from multiple sources, the alimony interaction, college costs, potential deviations. Schedule a free consultation to get guidance specific to your situation.

Frequently Asked Questions

How much child support will I pay in Massachusetts?

There is no single answer. Massachusetts uses the income shares model, which depends on both parents’ gross incomes, the number of children, the parenting time arrangement, and costs like health insurance and childcare. The 2025 guidelines cover combined incomes up to $450,000 per year. For a rough estimate, use the state’s official guidelines worksheet or our child support calculator.

Does 50/50 custody eliminate child support in Massachusetts?

No. Equal parenting time reduces the support amount through the parenting time adjustment, but it does not eliminate it when there is an income disparity between parents. The higher-earning parent still pays a reduced amount to help equalize the child’s standard of living in both homes.

Can Massachusetts courts order parents to pay for college?

Yes. Under MGL Chapter 208, Section 28, courts can order support for children between ages 18 and 23 who are domiciled with a parent and principally dependent on that parent. For children 21 to 23, enrollment in an undergraduate educational program is required. No parent can be ordered to pay more than 50% of UMass-Amherst in-state costs unless the court makes written findings that a higher amount is appropriate.

What happens if my ex is not reporting all of their income?

The court can impute income based on evidence of the parent’s assets, lifestyle, expenses, and spending patterns. For self-employed parents, the court scrutinizes business deductions to determine whether they are genuinely necessary to produce income. The court may also adjust imputed income upward to account for the absence of taxes on unreported income.

How do I modify child support in Massachusetts?

File a Complaint for Modification with the Probate and Family Court that issued the original order. You must show a material and substantial change in circumstances — such as a job loss, income change, or updated guidelines producing a different amount. The filing fee is $50 plus $5 for a summons and $35-$45 for service. Modifications take effect from the filing date, not retroactively.

Does a new spouse’s income affect child support in Massachusetts?

A new spouse’s income is excluded from the base child support calculation. However, the court may consider it as a factor when deciding whether to deviate from the guidelines amount — for example, if a new spouse’s income significantly reduces a parent’s living expenses, that could be relevant to a deviation argument.

How This Guide Was Researched

This guide was created by reviewing publicly available legal information from official state statutes, judiciary websites, court resources, and family law publications. The goal is to explain family law topics in plain English so readers can better understand the process before speaking with an attorney.

Sources and Legal References

This guide is based on publicly available legal information and official sources, including:

• 2025 Child Support Guidelines (Mass.gov)
• 2025 Guidelines Section I: Income Definition (Mass.gov)
• 2025 Guidelines Section II: Factors to Be Considered (Mass.gov)
• MGL Chapter 208, Section 28 (malegislature.gov)
• Probate and Family Court Filing Fees (Mass.gov)
• How to Fill Out the Child Support Guidelines Worksheet (MassLegalHelp)

Official Massachusetts Resources

• Massachusetts Probate and Family Court
• 2025 Child Support Guidelines and Worksheet
• Massachusetts DOR Child Support Enforcement
• Massachusetts Law About Child Support Over Age 18

For more about how we research our guides, see our editorial policy and sources methodology.

Related Guides

Learn more about related family law topics:

• Divorce in Massachusetts
• Child Custody in Massachusetts
• How Child Support Is Calculated
• Child Support with 50/50 Custody
• Modifying Child Support
• Child Support Enforcement
• Child Support Calculator

Last updated: April 2026. This guide summarizes general legal information based on publicly available sources and is provided for educational purposes only. It does not constitute legal advice. For advice specific to your situation, consult a licensed attorney in your state.