Child support is one of the most important financial issues in a divorce, separation, or child custody case. The amount of child support a parent pays is generally determined using state child support guidelines that consider the parents’ income, the number of children, parenting time, health insurance, child care costs, and other financial circumstances.
Child support is not simply a payment that one parent chooses to make to the other parent. Once a court enters a child support order, the amount becomes a legal obligation, and failing to pay can result in serious consequences, including collection actions, wage withholding, interest, license restrictions, and other enforcement measures.
Although every state has its own child support laws and guidelines, the basic calculation follows several common principles.
What Determines How Much Child Support You Pay?
The exact child support calculation depends on the state, but the following factors commonly play a major role:
- Both parents’ income
- Number of children
- Parenting time or overnight visits
- Health insurance costs
- Work-related child care expenses
- Other children the parents are legally responsible for supporting
- Certain taxes and allowable deductions
- Extraordinary medical or educational expenses
- Whether either parent receives certain benefits
- Whether the parents have substantially equal parenting time
The calculation is normally performed using a state-approved child support worksheet, formula, calculator, or guideline schedule.
The court may then approve the guideline amount or, when permitted by state law, order a different amount based on specific circumstances.
Does Child Support Consider Both Parents’ Income?
In most states, yes.
Most states use an income-shares model. Under this system, the court considers the income of both parents and estimates the amount that would ordinarily be spent on the child if the parents lived together.
The combined income is used to determine a basic support obligation. That obligation is then allocated between the parents based on their respective incomes and other factors.
For example, suppose:
- Parent A earns $6,000 per month
- Parent B earns $4,000 per month
- Combined monthly income is $10,000
Parent A earns 60% of the combined income, while Parent B earns 40%.
If the applicable state guideline establishes a $2,000 basic monthly child-support obligation for the children, the starting allocation could be approximately:
- Parent A: 60% = $1,200
- Parent B: 40% = $800
That does not necessarily mean Parent A will simply pay Parent B $1,200.
Parenting time, health insurance, child care, existing support obligations, and other adjustments can change the final transfer payment.
This is a simplified example. Actual child support calculations use the specific state’s guideline formula and definitions of income.
Which States Use the Income-Shares Model?
The income-shares approach is used by the large majority of states.
Examples include:
- Alabama
- Arizona
- Arkansas
- California
- Colorado
- Florida
- Georgia
- Idaho
- Illinois
- Indiana
- Iowa
- Kansas
- Kentucky
- Louisiana
- Maine
- Maryland
- Massachusetts
- Michigan
- Minnesota
- Missouri
- Nebraska
- New Jersey
- New Mexico
- New York
- North Carolina
- Ohio
- Oklahoma
- Oregon
- Pennsylvania
- Rhode Island
- South Carolina
- South Dakota
- Tennessee
- Utah
- Vermont
- Virginia
- Washington
- West Virginia
- Wyoming
The exact formula and income definitions differ from state to state.
Percentage-of-Income Child Support States
Some states use a percentage-of-income model, in which child support is calculated primarily by applying a guideline percentage to the income of the parent responsible for paying support.
Examples include:
- Alaska
- Mississippi
- Nevada
- North Dakota
- Texas
- Wisconsin
These states do not all use an identical formula. Each state has its own rules concerning income, deductions, additional expenses, and parenting arrangements.
What Is the Melson Formula?
A smaller number of states use the Melson Formula, which is a more detailed child support model designed to account for the parents’ basic needs as well as the children’s needs.
Delaware and Hawaii use the Melson Formula, while Montana also uses a Melson-based model.
This is one reason it is not possible to use a single nationwide child support calculator and expect an accurate result.
What Counts as Income for Child Support?
Child support income is usually broader than a parent’s regular paycheck.
Depending on state law, income may include:
- Wages
- Salaries
- Overtime
- Bonuses
- Commissions
- Self-employment income
- Business income
- Rental income
- Investment income
- Pension income
- Retirement benefits
- Social Security benefits
- Unemployment benefits
- Workers’ compensation
- Certain disability benefits
- Interest
- Dividends
- Other recurring sources of income
The exact definition of income is different in each state.
This becomes especially important when a parent is self-employed or owns a business.
Child Support for Self-Employed Parents
Calculating child support can be more complicated when a parent owns a business.
A business owner may receive money through:
- Salary
- Owner distributions
- Business profits
- Commissions
- Contract work
- Rental income
- Other business-related payments
The court may examine business records to determine actual income.
Documents that may be relevant include:
- Tax returns
- W-2 forms
- 1099 forms
- Profit-and-loss statements
- Bank statements
- Business financial statements
- Payroll records
- Accounting records
Business expenses can also require careful examination because a tax deduction does not automatically mean the expense should be excluded from income for child support purposes.
Can Child Support Be Based on Imputed Income?
Yes.
A parent cannot necessarily avoid child support simply by choosing not to work or by intentionally earning substantially less than they reasonably could.
Some states allow a court to impute income when a parent is voluntarily unemployed or underemployed under circumstances covered by the state’s law.
For example, a parent who previously earned $80,000 per year may not automatically be able to reduce child support by voluntarily taking a substantially lower-paying job simply to reduce the support obligation.
However, legitimate unemployment, disability, layoffs, career changes, or other circumstances may be treated differently.
The rules for imputing income vary significantly by state.
Does Custody Affect Child Support?
Yes.
Custody and parenting arrangements can have a major effect on child support.
The terminology differs between states. Courts may use terms such as:
- Legal custody
- Physical custody
- Sole custody
- Joint custody
- Shared custody
- Parenting time
- Residential custody
- Time-sharing
- Shared parenting
What matters financially is often how much time the child spends with each parent and how the state’s child support guidelines account for that parenting arrangement.
The ABA’s current 50-state comparison shows that many states have a specific mechanism for considering shared parenting time in their child-support calculation. Other states do not use a separate formula but allow parenting time to be considered when determining whether to deviate from the guideline amount.
Does 50/50 Custody Mean No Child Support?
No.
Equal or nearly equal parenting time does not automatically eliminate child support.
If one parent earns substantially more than the other, child support may still be owed even when the child spends approximately equal time with both parents.
For example:
Parent A earns $100,000 per year.
Parent B earns $40,000 per year.
The parents have approximately equal parenting time.
Depending on the state’s formula, Parent A may still owe child support because the parents have substantially different incomes.
Some states use specific shared-parenting formulas, while others treat substantial parenting time as a factor in determining the guideline amount.
How Does Parenting Time Affect Child Support?
Parenting time can affect child support because the parent who has the child for more time may directly pay more of the child’s day-to-day expenses.
Some state formulas therefore provide an adjustment based on the number of overnights or the percentage of parenting time.
The adjustment is not the same everywhere.
For example, the ABA’s 2025 state comparison identifies specific parenting-time calculations in states including Florida, California, Texas, Louisiana, Alabama, Pennsylvania, Ohio, and many others, while some states use different approaches or discretionary adjustments.
This is why entering the wrong number of overnight visits into an online child support calculator can produce a substantially different result.
Child Care Costs and Child Support
Work-related child care can be added to the child support calculation.
Examples include:
- Daycare
- After-school care
- Before-school care
- Certain summer child-care expenses
- Other qualifying work-related child-care costs
Many states require qualifying child-care expenses to be included in the calculation, while other states allow the court to consider them without making them a mandatory component of the basic support calculation.
The expense may then be divided between the parents according to their respective income percentages or according to the state’s specific formula.
Health Insurance and Medical Expenses
Child support can also involve the child’s medical expenses.
A child support order may address:
- Health insurance
- Health insurance premiums
- Uninsured medical expenses
- Dental expenses
- Vision expenses
- Prescription costs
- Necessary medical treatment
In many cases, one parent is ordered to maintain health insurance for the child when reasonably available.
The parents may also be required to share uninsured medical expenses.
The exact percentage each parent pays depends on the state’s rules and the court order.
What About Special Needs or Extraordinary Expenses?
A child with significant medical, educational, or other special needs may require expenses beyond the basic child support amount.
Depending on state law, courts may consider:
- Special medical treatment
- Therapy
- Special education
- Private school
- Extraordinary transportation expenses
- Necessary equipment
- Other unusual child-related expenses
These expenses may be included in the support order or addressed separately.
Does Child Support Include College Expenses?
Not necessarily.
Most states do not automatically require a parent to pay college expenses as ordinary child support after the child reaches the applicable age of majority.
However, several states specifically address post-secondary education or allow certain educational support arrangements.
For example, the current 50-state comparison identifies statutory provisions concerning college or post-secondary support in states including Connecticut, Illinois, Indiana, Massachusetts, New Jersey, New York, Oregon, Utah, Washington, and West Virginia, among others.
Parents can also sometimes agree to contribute toward college expenses even where the state does not automatically require it.
How Many Children Affect Child Support
The number of children is a major factor in most child support formulas.
A parent supporting:
- One child
- Two children
- Three children
- Four or more children
will generally have a different support obligation.
The increase is not necessarily a simple multiplication of the one-child amount.
Each state’s guideline schedule or formula determines how the obligation changes as the number of children increases.
What If a Parent Has Children From Another Relationship?
Existing support obligations can affect a child support calculation.
For example, a parent may already have a legal obligation to support children from a previous relationship.
Some state guidelines allow adjustments for other children or existing child support orders.
The treatment varies by state.
This is important because two parents earning the same amount may have different child support obligations if one parent has additional legally supported children.
Does Child Support Change if Someone Loses Their Job?
It can, but child support does not automatically change simply because someone loses a job.
Usually, the existing child support order remains in effect until it is modified through the legally required process.
Depending on state law, a substantial change in circumstances may justify a modification.
Examples can include:
- Job loss
- Major reduction in income
- Significant increase in income
- Disability
- Major change in parenting time
- Change in child-care expenses
- Change in health insurance costs
- A child’s substantial change in needs
A parent should not simply stop paying because income has decreased.
Can Child Support Be Modified?
Yes, child support can generally be modified when the legal requirements for modification are met.
The exact standard varies by state.
A modification may be appropriate when there has been a substantial or material change in circumstances recognized by state law.
Common reasons include:
- Significant income change
- Job loss
- Disability
- Change in custody or parenting time
- Change in child-care costs
- Change in health insurance
- Change in the child’s needs
The parent requesting the modification generally must follow the state’s legal procedure rather than changing the payment amount independently.
What Happens if Child Support Is Not Paid?
Unpaid child support becomes child support arrears.
A parent who falls behind may face enforcement measures authorized by state and federal law.
Possible enforcement actions can include:
- Wage garnishment or income withholding
- Interception of tax refunds
- Liens
- Seizure of certain assets
- Suspension of driver’s licenses
- Suspension of professional licenses
- Credit reporting
- Passport restrictions in qualifying cases
- Contempt proceedings
- Additional penalties or interest
The exact remedies depend on the amount owed and applicable state and federal law.
How Is Child Support Collected?
Many child support orders use income withholding.
Instead of the paying parent manually sending the entire payment each month, an amount may be withheld from wages and sent through the state’s child support collection system.
This can make payments easier to track and can reduce disputes about whether payments were made.
Other payment methods may be available depending on the state.
Child Support and Taxes
Child support is different from a tax deduction.
Generally, paying child support does not mean that the parent can simply deduct the payment from taxable income as a federal tax deduction.
Child support is also different from claiming a child as a dependent.
Parents should address tax issues separately from the child support calculation because federal tax rules and state family-law orders can involve different rules.
How to Estimate Child Support
A basic estimate requires information such as:
Parent 1 monthly income
Parent 2 monthly income
Number of children
Parenting-time schedule
Health insurance cost for the children
Work-related child-care costs
Existing child support obligations
Other allowable deductions
The information is then entered into the applicable state’s child support worksheet or calculator.
A nationwide child support calculator cannot accurately determine a final support obligation because each state uses its own guidelines and calculations.
Examples of How State Child Support Rules Differ
The differences between states are significant.
Florida
Florida uses an income-shares model and has a specific mechanism for considering shared parenting time. Work-related child care is a mandatory consideration in the guideline calculation.
Texas
Texas uses a percentage-of-obligor-income model rather than the income-shares model used by most states. Parenting time and child-care expenses can be considered when determining whether to deviate from the guideline amount.
California
California uses an income-shares approach that incorporates the parents’ incomes and the approximate percentage of time the higher-earning parent has primary physical responsibility for the children.
Louisiana
Louisiana uses an income-shares model and provides a shared-custody calculation for situations involving approximately equal physical custody. Its rules also address child-care expenses.
Mississippi
Mississippi uses a percentage-of-income model. Shared parenting arrangements and child-care expenses may be considered as factors when determining whether to deviate from the guideline amount.
Nevada
Nevada uses a percentage-of-income model and has specific provisions for calculating support when parents have joint physical custody.
Wisconsin
Wisconsin primarily uses a percentage-of-income approach, but its shared-placement formula considers both parents’ incomes when qualifying parenting-time requirements are met.
Child Support Guidelines by State
Because child support laws are state-specific, anyone calculating child support should use the current guideline for the state where the case is being handled.
The relevant state may determine:
- What counts as income
- Which deductions are allowed
- How parenting time affects support
- How health insurance is treated
- How child-care expenses are divided
- How support for additional children is considered
- When the guideline amount can be changed
- When support ends
State guidelines can also be amended. Several states made child support guideline changes during 2025, including Colorado, Iowa, Massachusetts, New Jersey, Pennsylvania, Virginia, and Washington.
Child Support Calculator: What You Need Before Using One
If you are using an online child support calculator, have the following information available:
- State where the case is filed
- County, if required
- Gross monthly income for both parents
- Number of children
- Number of overnights with each parent
- Health insurance premiums
- Work-related child-care expenses
- Existing child support orders
- Other legally supported children
- Other applicable income or deductions
The more accurate the information entered into the calculator, the more useful the estimate will be.
An online estimate is not necessarily the amount a court will ultimately order.
Child Support Is Separate From Child Custody
Child support and custody are related but legally separate issues.
A parent generally cannot stop paying child support because the other parent denied parenting time.
Likewise, a parent generally cannot refuse parenting time simply because child support is unpaid.
Custody, parenting time, and child support are separate legal issues, although changes in parenting arrangements can affect the child support calculation.
Child Support Checklist
When preparing for a child support case, gather:
- Recent pay stubs
- Tax returns
- W-2s
- 1099s
- Business income records
- Bank statements
- Child-care invoices
- Health insurance information
- Medical expense records
- Existing child support orders
- Parenting-time schedules
- Records of other support obligations
- Documentation of significant child-related expenses
Accurate financial information is particularly important when income comes from self-employment, commissions, bonuses, investments, rental property, or a business.
Key Takeaways About Child Support
Child support is generally calculated using a state’s statutory guidelines rather than an arbitrary amount selected by either parent.
The most important factors commonly include:
- Both parents’ income
- Number of children
- Parenting time
- Child-care expenses
- Health insurance
- Medical expenses
- Other support obligations
- State-specific deductions and adjustments
Most states use an income-shares model, but some use percentage-of-income formulas or the Melson Formula. Parenting time is also treated differently from state to state.
For that reason, the most accurate child support calculation requires the specific state’s current guidelines and financial information for both parents.