How Child Support Is Actually Calculated in Florida

By Joshua C. Miller, Esq. · Green Bench Law, PLLC · Informational only — not legal advice

Two myths dominate first consultations about child support. Myth one: "the judge just picks a number." Myth two: "we can agree to whatever we want." Neither is true. Florida child support is a statutory formula — the income shares model in section 61.30, Florida Statutes — and while parents have some room to agree, courts must still review any agreement against the guideline amount.

The premise of the income shares model is simple: a child should receive the same proportion of parental income that they would have received if the household had stayed together. Here's how the math works, step by step.

Step 1: Determine each parent's gross income

Gross income is broad. It includes salary and wages, bonuses, commissions, overtime, tips, business and self-employment income, disability and workers' compensation benefits, unemployment, pension and retirement income, Social Security benefits, spousal support received from a prior marriage (or awarded in the current case), rental income, and recurring investment income.

Step 2: Subtract allowable deductions to get net income

From gross income, each parent deducts items such as income taxes (properly calculated, not just what's withheld), FICA, mandatory union dues, mandatory retirement contributions, health insurance premiums for the parent (not the child), court-ordered support actually paid for other children, and spousal support paid.

Step 3: Combine net incomes and apply the guideline schedule

The parents' net incomes are added together, and the statute's guideline schedule sets a basic support obligation for that combined income and the number of children. Each parent is then responsible for a share of that obligation proportional to their share of the combined income. If you earn 60% of the combined net income, you're responsible for 60% of the basic obligation.

Step 4: Add child care and health insurance

Work-related child care costs and the child's health insurance premium are added on top of the basic obligation and allocated between the parents in the same proportional shares. Uncovered medical expenses are typically allocated the same way.

Step 5: Adjust for substantial time-sharing

This is where parenting schedules and money intersect. When a parent exercises at least 20% of the overnights (73 or more overnights per year), the statute requires a different calculation — often called the "gross-up" method — that accounts for both households' costs and each parent's overnight percentage. With Florida's presumption of equal time-sharing now in place, this adjusted calculation applies in a large share of new cases, and small changes in the overnight count can move the number meaningfully.

Can the court deviate from the guidelines?

Yes, within limits. A court may adjust the guideline amount by up to 5% in either direction after considering relevant factors. Deviations beyond 5% require written findings explaining why the guideline amount would be unjust or inappropriate — for example, extraordinary medical or educational expenses, the child's independent income, or seasonal variations in a parent's income.

Practical takeaways

• Financial disclosure drives everything. The formula is only as good as the inputs. Complete, accurate financial affidavits — and scrutiny of the other side's — matter more than argument.
• Overnights are money. Time-sharing schedules and support amounts should be negotiated together, never in isolation.
• Self-employment cases get complicated. Determining true income from a business often requires digging into records; this is where experienced counsel earns their fee.
• Orders can be modified. A substantial, permanent, involuntary change in circumstances can support modification — but until a court changes the order, the existing amount keeps accruing.