Child Support Calculator: Estimate Monthly Child Support Obligations
Estimate child support payments based on income, custody arrangements, and state guidelines. Understand how courts calculate support obligations.
Child support is one of the most litigated areas of family law — and the amounts matter enormously to families on both sides. Courts don't pull these numbers out of thin air; they follow state guidelines based on income, custody, and specific circumstances. The CalcHub Child Support Calculator provides estimates under each state's approach, so you enter negotiations or court with realistic expectations.
Child support determinations involve legal and factual questions beyond any calculator. Consult a family law attorney for guidance on your specific situation.How Courts Calculate Child Support: Two Main Models
Income Shares Model (Used by Most States)
Both parents' incomes are combined to determine a total support obligation, then each parent contributes proportionally to their share of combined income.
Example:- Parent A (custodial): $4,000/month net income
- Parent B (non-custodial): $6,000/month net income
- Combined: $10,000/month
- Basic support for 2 children (per state table): ~$1,800/month
- Parent B's share: 60% × $1,800 = $1,080/month payable to Parent A
Percentage of Income Model (Used by Some States)
A fixed percentage of the non-custodial parent's income:
| State | 1 Child | 2 Children | 3 Children |
|---|---|---|---|
| Texas | 20% | 25% | 30% |
| Wisconsin | 17% | 25% | 29% |
| Illinois (old) | 20% | 28% | 32% |
What Goes Into "Income"
Both models require defining each parent's gross or net income, which typically includes:
- Wages and salary
- Self-employment income (net of legitimate business expenses)
- Bonuses and commissions
- Rental income
- Investment income
- Pension and Social Security
Common Adjustments
| Adjustment | Effect |
|---|---|
| Shared custody (40%+ overnights) | Reduces support significantly |
| Child's health insurance premium | May be added to obligor's requirement |
| Childcare costs | Split between parents proportionally |
| Special needs or extraordinary expenses | Additional amount on top of guideline |
| Other children from other relationships | May reduce available income |
Can parents agree to a support amount below the guideline?
In most states, parents can agree to any amount, but courts must approve it and will reject agreements they believe leave the child under-supported. Agreements above guidelines are generally approved without issue.
How often can child support be modified?
Most states allow modification when circumstances have substantially changed — typically defined as a 10–20% change in income or a significant change in custody. You can't just request annual changes unless the change is significant.
Does child support end at 18?
In most states, yes — support ends at the age of majority (18 or 19) unless the child is still in high school or has special needs. Some states extend support through college under certain circumstances.
Related Calculators
- Alimony Calculator — Calculate spousal support alongside child support
- Settlement Calculator — Factor support payments into overall divorce financial settlement
- Legal Interest Calculator — Calculate interest on unpaid support arrears