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Child Support Calculator

Estimate child support payments using the Income Shares Model based on both parents incomes, number of children, custody arrangement, and additional expenses.

Calculation Model & Incomes

$
$
nights/yr
Quick custody schedule presets:

Children’s Medical & Childcare

$
$

Prior Support Deductions

$
$

Estimated monthly child support (Income Shares Model)

$1,254.00 / mo

$15,048.00 per year • Parent 1 pays Parent 2

Monthly child support and expenses breakdown

  • Base child support$1,531.000.6%
  • Work-related childcare$600.000.3%
  • Children health insurance$250.000.1%

Total basic support obligation

$1,531.00

Combined spending for 1 child based on $9,500.00/mo family income

Parent 1 income share

0.6%

Parent 2 earns remaining 0.4% of combined income

Parent 1 net income post-support

$4,496.00 / mo

$53,952.00/yr after support & direct child costs

Parent 2 net income post-support

$4,154.00 / mo

$49,848.00/yr after support & direct child costs

Parenting time schedule

73 nights (0.2%)

Standard visitation / sole custody schedule (< 92 overnights)

Total add-on expenses

$850.00

Childcare: $600.00 • Health: $250.00

Guideline Model Comparison

Statutory ModelMonthlyAnnualKey Assumptions
Income Shares Model (41+ States)Active$1,254.00$15,048.00Standard sole custody income proportion
Percentage of Obligor Income (TX/WI)$1,550.00$18,600.000.2% flat rate on obligor income for 1 child

How child support is calculated

Step-by-step breakdown using the standard Income Shares guideline model.

  1. Calculate combined adjusted monthly income

    Itotal=max⁡(0,Parent 1 Gross−Deductions1)+max⁡(0,Parent 2 Gross−Deductions2)I_{\text{total}} = \max(0, \text{Parent 1 Gross} - \text{Deductions}_1) + \max(0, \text{Parent 2 Gross} - \text{Deductions}_2)

    Parent 1 has an adjusted monthly income of $6,000.00 and Parent 2 has an adjusted monthly income of $3,500.00, producing a combined family income of $9,500.00.

  2. Determine proportional income shares

    S1=I1Itotal,S2=I2ItotalS_1 = \frac{I_1}{I_{\text{total}}}, \quad S_2 = \frac{I_2}{I_{\text{total}}}

    Parent 1 contributes 0.6% of the family income, while Parent 2 contributes 0.4%.

  3. Determine the basic child support obligation (BCSO)

    BCSO=f(Itotal,Children)\text{BCSO} = f(I_{\text{total}}, \text{Children})

    Based on standard economic expenditure tables for 1 child at $9,500.00 monthly income, the basic child support obligation is $1,531.00 per month.

  4. Adjust for parenting time and overnight custody split

    Base Obligation1=BCSO×S1\text{Base Obligation}_1 = \text{BCSO} \times S_1

    Under standard sole custody (73 overnights), Parent 1’s basic share is 0.6% × $1,531.00 = $967.00.

  5. Add mandatory add-ons and credit direct payments

    Final Payment=max⁡(0,Base Obligation1+S1×Add-ons−Direct Expenses Paid1)\text{Final Payment} = \max(0, \text{Base Obligation}_1 + S_1 \times \text{Add-ons} - \text{Direct Expenses Paid}_1)

    Total add-ons (childcare: $600.00 + health: $250.00) equal $850.00. Parent 1’s add-on share is $537.00, and Parent 1 pays $250.00 directly out of pocket, resulting in a final monthly payment of $1,254.00.

Child support estimations are calculated using benchmark economic schedules based on the Income Shares Model (utilized by over 40 US states) and statutory Percentage of Obligor Income guidelines for 2026. Official state child support worksheets may incorporate additional state-specific adjustments such as self-support reserves, low-income minimum orders, extraordinary medical expenses, and judicial discretion.
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How Child Support Is Calculated in the United States

Child support is a court-ordered periodic payment made by one parent to the other to ensure children continue to receive the financial benefits of both parents’ incomes following a separation, divorce, or paternity establishment. In the United States, child support guidelines are established at the state level, with 41 states utilizing the Income Shares Model, 6 states using the Percentage of Obligor Income Model, and 3 states relying on the Melson Formula.

When structuring separation agreements, child support is frequently calculated in tandem with spousal support. If you are evaluating post-divorce income transitions, you can estimate maintenance using the alimony calculator. To prepare for ongoing child-rearing costs such as daycare, medical supplies, and education, refer to the child cost calculator, or organize your complete post-separation household budget with the budget calculator and the 50-30-20 rule budget calculator.

The Three Main Child Support Models

Every US jurisdiction adheres to one of three statutory child support frameworks:

1. The Income Shares Model (41 States)

The Income Shares Model operates on the principle that a child should receive the exact same proportion of parental income that they would have received if the parents had remained together in an intact household. The court combines both parents’ gross or net monthly incomes, references an economic consumption schedule (such as the Betson-Rothbarth expenditure studies) to determine the basic child support obligation, and assigns each parent a percentage of that obligation based on their relative share of total combined income.

2. Percentage of Obligor Income Model (6 States)

States like Texas, Wisconsin, Mississippi, and Nevada utilize a flat or graduated percentage applied exclusively to the non-custodial paying parent’s net monthly resources, regardless of how much the custodial parent earns. For instance, Texas statutory guidelines prescribe 20% of net resources for 1 child, 25% for 2 children, 30% for 3 children, 35% for 4 children, and 40% for 5 or more children (subject to statutory monthly income caps).

3. The Melson Formula (3 States)

Originating in Delaware and also used in Hawaii and Montana, the Melson Formula is a specialized variation of the Income Shares Model. It first allocates a strict self-support reserve to each parent so they can maintain basic personal subsistence. Once self-support needs are met, remaining income covers the child’s primary support needs, followed by a standard of living adjustment (SOLA) percentage if excess income remains.

Step-by-Step Income Shares Formula

Under the standard Income Shares methodology, the calculation follows five mathematical phases:

Step 1: Calculate Combined Monthly Adjusted Income

Gross earnings from employment, business profit, pensions, and investments are adjusted by deducting pre-existing court-ordered child support and alimony paid for prior relationships:

Itotal=(I1−D1)+(I2−D2)I_{\text{total}} = (I_1 - D_1) + (I_2 - D_2)

Step 2: Determine Individual Income Shares

Each parent’s proportional contribution to the combined family income is computed:

S1=I1Itotal,S2=I2ItotalS_1 = \frac{I_1}{I_{\text{total}}}, \quad S_2 = \frac{I_2}{I_{\text{total}}}

Step 3: Lookup Basic Child Support Obligation (BCSO)

Using economic spending tables, the state identifies the baseline expenditure required to feed, clothe, and house the children for that specific combined income level:

BCSO=f(Itotal,Nchildren)\text{BCSO} = f(I_{\text{total}}, N_{\text{children}})

Step 4: Incorporate Mandatory Add-On Expenses

Work-related childcare (daycare or after-school care) and the child’s portion of health insurance premiums are added to the basic obligation and shared proportionally:

Total Support Need=BCSO+Childcare+Health Insurance\text{Total Support Need} = \text{BCSO} + \text{Childcare} + \text{Health Insurance}

Step 5: Apply Parenting Time and Credit Direct Payments

The paying parent’s gross obligation is calculated, direct out-of-pocket payments (such as health insurance premiums paid directly to the carrier) are credited, and the final net monthly payment is determined:

Net Monthly Support=max⁡(0,S1×Total Support Need−Direct Expenses Paid1)\text{Net Monthly Support} = \max(0, S_1 \times \text{Total Support Need} - \text{Direct Expenses Paid}_1)

How Custody and Overnight Schedules Impact Payments

In most modern state guidelines, physical custody arrangements significantly influence the final support order. Courts recognize that when a non-custodial parent hosts a child for substantial overnights, they incur direct daily expenses for groceries, utilities, and transportation in their own home.

  • Sole Physical Custody (Under 25% or under 92 overnights): Standard guidelines presume the custodial parent bears primary direct living expenses. The paying parent contributes their full income share without overnight discounts.
  • Shared Physical Custody (25% to 50% or 92 to 182 overnights): Most states apply a shared custody cross-credit formula with a 1.50 multiplier (150% of the basic schedule) to account for dual household fixed overhead. Each parent’s theoretical obligation to the other is calculated based on the other parent’s time share, and the higher-earning parent pays the net difference.
  • Equal 50/50 Custody: Even with exactly equal parenting time (182.5 overnights each), child support is rarely $0 unless both parents earn identical incomes. The parent with higher earnings pays a calibrated offset to balance resources between the two homes.

Worked Example: Two-Child Shared Custody Calculation

Consider a family with two children where Parent 1 earns $6,000 monthly, Parent 2 earns $3,500 monthly, and they share custody with Parent 1 having 146 overnights (40% parenting time):

1. Combined Income: $6,000 + $3,500 = $9,500/month.

2. Income Shares: Parent 1 earns 63.16% ($6,000 / $9,500); Parent 2 earns 36.84% ($3,500 / $9,500).

3. Basic Obligation (2 Children): Economic schedule yields approximately $1,970/month.

4. Shared Custody Adjustment: Applying the 1.5x factor gives an adjusted pool of $2,955 ($1,970 × 1.5).

5. Cross-Credit Calculation: Parent 1’s obligation to Parent 2 for Parent 2’s 60% time is $2,955 × 0.6316 × 0.60 = $1,120. Parent 2’s obligation to Parent 1 for Parent 1’s 40% time is $2,955 × 0.3684 × 0.40 = $435. The net base cross-credit equals $685/month.

6. Add-Ons: If Parent 2 pays $600/mo daycare and Parent 1 pays $250/mo health insurance, Parent 1’s 63.16% share of the $850 total add-on pool is $537. Crediting the $250 healthcare premium already paid leaves an add-on payment of $287.

7. Total Monthly Payment: $685 (base) + $287 (add-on net) = $972 per month.

Frequently asked questions

Is child support tax-deductible for the payer or taxable to the recipient?
No. Under United States federal tax law (IRC Section 71), child support payments are neither tax-deductible for the paying parent nor taxable gross income to the receiving parent. Child support is transferred using after-tax dollars.
When can a child support order be legally modified?
Either parent may petition family court for a child support modification whenever there is a substantial, material change in circumstances. Common qualifying grounds include a 15% to 20% involuntary change in parental income, job loss, disability, changes in physical custody overnights, or significant adjustments in healthcare and childcare expenses.
At what age does child support legally end?
In most US states, child support terminates when the child reaches the age of majority (typically 18 years old) or graduates from high school, whichever occurs later (up to age 19 in many states). In certain states like New York, support continues until age 21, and parents of children with severe disabilities may be ordered to provide indefinite support.
How do self-employment and overtime factor into income calculations?
Courts calculate gross income for self-employed parents by taking total business revenues and subtracting ordinary, necessary operational expenses (excluding non-cash depreciation). Regular, predictable overtime and bonuses are generally included, whereas speculative, sporadic earnings may be averaged across 2 to 3 prior tax returns.
What happens if a parent voluntarily becomes unemployed or underemployed?
If a judge determines that a parent has intentionally quit a job or reduced their working hours to avoid paying child support, the court may impute income. The judge assigns an estimated earning capacity based on the parent’s work history, educational credentials, and prevailing local wage rates.
Are my financial calculations saved or shared?
No. All calculations run entirely on your device inside your web browser. Your inputs are encoded into the URL parameters so you can bookmark, save, or share your custom calculation without storing sensitive financial data on any external server.

Resources and references

The formulas and methods in this calculator were checked against these independent sources.