Co-Parenting Expense Calculator
Splitting 50/50 when one parent earns three times more isn't fair — it just feels simple. This calculator splits child expenses proportionally by income, by custody time, or a hybrid that weighs both. Plug in education, medical, childcare, and activity costs to get a clear number each parent owes, so the conversation stays about the kids and not the math.
$310K to age 18
Avg Child Cost
Most common method
Income Share
Custodial parent default
Tax Filer
Income/custody change
Recalc Trigger
Co-parents typically split child expenses proportionally to income. If Parent A earns $6,000/month and Parent B earns $4,000/month, Parent A pays 60% of shared expenses like education, healthcare, and activities. Enter both incomes and expenses below for a fair breakdown.
Parents
Parent 1 has 50% custody time
Child Expenses
Split Method
Each parent pays proportionally to their income. Higher earner pays more.
Coparenting Cost Split — Income-Share Reference
Typical proportional splits when parents have different incomes. The higher earner covers a proportionally larger share of shared costs (childcare, healthcare, activities).
| Parent A Income | Parent B Income | A Share | B Share |
|---|---|---|---|
| $50,000 | $50,000 | 50% | 50% |
| $60,000 | $40,000 | 60% | 40% |
| $80,000 | $40,000 | 67% | 33% |
| $100,000 | $50,000 | 67% | 33% |
| $120,000 | $30,000 | 80% | 20% |
How This Calculator Works
Enter Your Details
Fill in amounts, people, and preferences. Takes under 30 seconds.
Get Fair Results
See an instant breakdown with data-driven calculations and Fairness Scores.
Share & Settle
Copy a shareable link to discuss results with everyone involved.
Frequently Asked Questions
How should co-parents split expenses?
The most common approach is income-proportional: if Parent A earns 60% of combined income, they pay 60% of shared expenses. This is fairer than 50/50 when incomes differ significantly. Our calculator supports income-based, equal, custody-based, and hybrid methods.
What expenses should co-parents split?
Typically split: education (tuition, supplies, tutoring), healthcare (insurance, copays, dental), childcare (daycare, babysitting), extracurricular activities, clothing, and food for the child. Expenses during your own custody time (food, housing) usually aren't split.
How does custody affect expense splitting?
With 50/50 custody, expenses are usually split by income ratio. With 70/30 custody, the parent with less time may pay more in child support but split additional expenses differently. Our hybrid method weighs both income and custody time.
Is this the same as child support?
No — child support is a court-ordered payment from one parent to the other. This calculator is for splitting additional expenses (medical bills, school fees, activities) that come up beyond the base support amount. Many co-parents need both.
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Related Guide
The Complete Guide to Fair Division
Income-proportional splits for childcare, education, and medical costs between co-parents.