How Child Support Is Calculated in Every State (2026 Guide)
Learn how child support is calculated in all 50 states. Understand the three calculation models — income shares, percentage of income, and the Melson formula — with real examples, state-specific rules, and factors that affect your payment.
1. The Three Child Support Models
Every state in the US uses one of three models to calculate child support. The model your state uses determines which parent's income matters, how much weight custody time gets, and ultimately how much is owed.
Income Shares
41 states
Both parents' incomes are combined. Each parent pays a proportional share of the total obligation based on their percentage of combined income.
Percentage of Income
6 states
Only the non-custodial parent's income is used. A fixed percentage is applied based on the number of children.
Melson Formula
3 states
Similar to income shares but first ensures each parent can meet their own basic needs (self-support reserve) before calculating child support.
Which States Use Which Model?
Percentage of Income: Alaska, Mississippi, Nevada, North Dakota, Texas, Wisconsin
Melson Formula: Delaware, Hawaii, Montana
State-Specific: California (algebraic formula), New York (CSSA hybrid)
Income Shares: All other states + DC (Alabama, Arizona, Arkansas, Colorado, Connecticut, Florida, Georgia, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Missouri, Nebraska, New Hampshire, New Jersey, New Mexico, North Carolina, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Utah, Vermont, Virginia, Washington, West Virginia, Wyoming)
3. Percentage of Income Model (6 States)
This is the simplest model. Only the non-custodial parent's income is considered. A flat percentage is applied based on the number of children:
| Children | Texas | Wisconsin | Mississippi | Alaska | Nevada |
|---|---|---|---|---|---|
| 1 | 20% | 17% | 14% | 20% | 18% |
| 2 | 25% | 25% | 20% | 27% | 25% |
| 3 | 30% | 29% | 22% | 33% | 29% |
| 4 | 35% | 31% | 24% | 36% | 31% |
| 5+ | 40% | 34% | 26% | 39% | 33% |
Key Differences Between States
- Texas uses “net resources” (gross minus taxes, SS, Medicare, health insurance). Cap: $11,700/month net.
- Wisconsin uses gross income — no deductions at all.
- Mississippi uses adjusted gross (gross minus taxes and FICA).
- Alaska uses annual net income.
- Nevada uses gross income with tiered rates above $6,000/month.
Example: Texas Calculation
Non-custodial parent earns $6,000/month gross. After taxes and deductions, net resources = ~$4,800/month. Two children → 25% × $4,800 = $1,200/month.
4. Melson Formula (3 States)
Used by Delaware, Hawaii, and Montana, the Melson Formula is a three-step process that prioritizes each parent's ability to meet their own basic needs:
- Self-support reserve — Each parent's income is first reduced by a self-support amount (roughly $1,510/month) to ensure they can cover their own basic living expenses.
- Primary support — A basic child support need is calculated based on the child's age and the state's cost-of-living data. Each parent contributes proportionally from their remaining income.
- Standard of living adjustment — If either parent has income remaining after steps 1 and 2, a percentage of that excess is allocated to the child to share in the parent's standard of living.
The Melson Formula generally results in lower support amounts for low-income parents and higher amounts for high-income parents compared to the standard income shares model.
5. State-Specific Formulas: CA, TX, NY, FL, IL
California
California uses a unique algebraic formula: CS = K[HN - (H%)(TN)]
- HN = high earner's net monthly disposable income
- H% = percentage of time high earner has the children
- TN = total net monthly disposable income (both parents)
- K = income allocation factor based on total net income (ranges from ~0.165 to 0.25 for one child, multiplied for additional children)
Multi-child multipliers: 2 children = 1.6×, 3 = 2.0×, 4 = 2.3×, 5 = 2.5×
Texas
Percentage of income model. Flat percentages applied to net resources:
1 child = 20%, 2 = 25%, 3 = 30%, 4 = 35%, 5+ = 40%. Net resources cap: $11,700/month (effective September 2025). Maximum guideline support for 1 child: $2,340/month.
New York
Uses the Child Support Standards Act (CSSA) — a hybrid approach:
Percentages applied to combined parental income up to $193,000/year: 1 child = 17%, 2 = 25%, 3 = 29%, 4 = 31%, 5+ = 35%.
Each parent pays their proportional share. Self-support reserve: $21,546/year. Below this, minimum payment is $50/month.
Florida
Standard income shares model with a detailed statutory schedule (Fla. Stat. 61.30).
Shared custody adjustment kicks in at 73 overnights (20% of the year). The basic obligation is multiplied by 1.5 and each parent's share is offset by their parenting time percentage.
Illinois
Switched from percentage of income to income shares in 2017.
Uses adjusted net income (gross minus taxes, FICA, mandatory retirement, prior support). Shared parenting adjustment at 146 overnights (40%) — obligation is multiplied by 1.5 with offsets for duplicated expenses.
6. How Custody Affects Child Support
Parenting time has a significant impact on child support calculations in most states. The general principle: the more time you spend with your children, the less support you owe (because you're spending directly on them during that time).
Shared Custody Thresholds by State
Most states have a minimum overnight threshold that triggers a shared-custody adjustment:
Florida
73 nights (20%)
Indiana
52+ nights
North Carolina
123 nights
Illinois
146 nights (40%)
Wyoming
92 nights (25%)
Delaware
164 nights
50/50 Custody
Even with equal time, child support doesn't automatically drop to zero. If one parent earns significantly more than the other, they'll still owe support to equalize the child's standard of living between households. The amount is typically reduced substantially compared to sole custody, but the higher earner usually still pays something.
7. What Counts as Income
Courts cast a wide net when defining “income” for child support purposes. It's not just your W-2 salary:
Counted as Income
- Salary and wages
- Bonuses and commissions
- Self-employment income
- Rental income
- Investment income and dividends
- Social Security benefits
- Unemployment and disability
- Pension and retirement income
- Trust income
- Tips and overtime
Common Deductions
- Federal and state income taxes
- FICA (Social Security + Medicare)
- Mandatory retirement contributions
- Union dues
- Health insurance premiums (for parent)
- Prior child support orders
- Spousal support/alimony paid
Imputed Income
If a court finds that a parent is voluntarily unemployed or underemployed, it can “impute” income — meaning it assigns an income level based on the parent's education, work history, skills, and local job market. Quitting your job to reduce child support doesn't work.
8. Modifying Child Support
Child support orders aren't permanent. Either parent can request a modification if circumstances change significantly:
- Job loss or income reduction — involuntary job loss is the most common reason for modification
- Significant raise — either parent's income increasing substantially
- Change in custody — more or fewer overnights with either parent
- Child's needs change — medical issues, educational needs, aging out
- New children — some states allow adjustments for subsequent children
- Cost of living changes — some states have automatic COLA adjustments
Most states require at least a 10-20% change in the calculated amount to grant a modification. Until a modification is approved by the court, the original order remains in effect — you can't unilaterally reduce payments.
9. Real-World Examples
Example 1: Texas — One child, standard custody
Non-custodial parent earns $75,000/year gross (~$6,250/month).
- Net resources after taxes/FICA: ~$5,100/month
- One child = 20% of net resources
- Monthly support: ~$1,020
Example 2: New York — Two children, income disparity
Parent A: $120,000/year. Parent B: $50,000/year. Two children. Parent A is non-custodial.
- Combined income: $170,000 (under $193K cap)
- Two children = 25% × $170,000 = $42,500/year obligation
- Parent A's share: 70.6% × $42,500 = $30,000/year
- Monthly support: ~$2,500
Example 3: Florida — Two children, shared custody
Parent A: $6,000/month net. Parent B: $4,000/month net. 60/40 custody split (Parent A has 60%). Two children.
- Combined net: $10,000/month
- Basic obligation (approx): $10,000 × 28% = $2,800
- Shared custody adjustment (1.5×): $4,200
- Parent A's share: 60% × $4,200 = $2,520, offset by 60% parenting time
- Parent B's share: 40% × $4,200 = $1,680, offset by 40% parenting time
- Net payment from A to B: ~$840/month (significantly reduced from the ~$1,680 without shared custody)
The Bottom Line
Child support calculations vary dramatically by state. The same family earning the same income could owe $800/month in Mississippi and $2,500/month in New York. Understanding your state's model — and the specific inputs that matter — is critical for planning.
Use our Child Support Calculator for a quick estimate, but always consult a family law attorney for your specific situation. Courts have discretion to deviate from guidelines based on special circumstances, and there are nuances (like imputed income, extraordinary expenses, and prior orders) that no calculator can fully capture.
Disclaimer: This guide and calculator provide estimates for informational purposes only. They are not legal advice. Actual child support orders are determined by courts and may differ from these estimates.
Frequently Asked Questions
How much child support will I pay?
Child support depends on your state, both parents' incomes, the number of children, custody split, and additional costs like health insurance and childcare. Most states use the income shares model, where both parents' incomes are combined and each pays a proportional share of the total child support obligation. Use our calculator for a state-specific estimate.
Is child support based on gross or net income?
It depends on the state. Most income shares states start with gross income and allow deductions for taxes, FICA, mandatory retirement, and health insurance. Texas uses 'net resources' (gross minus taxes and certain deductions). California uses 'net disposable income.' Wisconsin uses gross income with no deductions.
Does 50/50 custody mean no child support?
Not necessarily. Even with equal parenting time, if there's a significant income difference between parents, the higher earner typically still pays child support. The amount is usually reduced compared to a sole custody arrangement, but it rarely drops to zero unless both parents earn similar incomes.
Can child support be changed after it's set?
Yes. Either parent can request a modification if there's a 'substantial change in circumstances' — such as job loss, significant raise, change in custody arrangement, or a child's changing needs. Most states require at least a 10-20% change in the calculated amount to grant a modification.
What happens if I don't pay child support?
Consequences for non-payment include wage garnishment, tax refund seizure, driver's license suspension, passport denial, credit damage, contempt of court charges, and potentially jail time. Child support is a court order and non-payment is taken very seriously.
Is child support tax-deductible?
No. Child support has never been tax-deductible for the payer or taxable income for the recipient. This is different from alimony, which was deductible for agreements signed before 2019 but lost its deduction under the Tax Cuts and Jobs Act.
How long does child support last?
In most states, child support continues until the child turns 18 or graduates high school, whichever is later. Some states extend support to 19 or 21 if the child is still in high school or college. New York can extend support to age 21. A few states may require support for college expenses.
What if the other parent is hiding income?
Courts can impute income to a parent who is voluntarily unemployed or underemployed. This means the court assigns an income level based on the parent's education, work history, and local job market. Courts may also subpoena tax returns, bank statements, and business records to verify actual income.