Ohio uses the Ohio Child Support Guidelines (ORC § 3119) to determine child support obligations. Under the Income Shares model, both parents' incomes are combined to estimate what the family would have spent on the child if the household were intact. The obligation is then divided proportionally based on each parent's contribution to combined gross income.

Ohio has several distinctive features in its child support system. Ohio recently updated its child support schedule (effective March 2019) for the first time in decades. The state uses a detailed "Child Support Computation Worksheet" that must accompany every support order. Ohio includes a specific "10% deviation" rule — courts can't deviate more than 10% without additional findings.

Ohio bases calculations on gross income — meaning income before taxes and deductions. This includes wages, salaries, commissions, bonuses, self-employment income, and other sources. The self-support reserve in Ohio is $1,275/month, ensuring the paying parent retains enough income to cover basic living expenses.

Ohio recognizes "Shared Parenting" when the non-custodial parent has the children for at least 128 overnights per year (approximately 35% of the time). When this threshold is met, the standard child support formula is adjusted to reflect the increased direct expenses borne by both parents.

Under Ohio's Income Shares approach, the shared parenting adjustment typically calculates each parent's obligation based on their income share, then applies a credit or cross-calculation that accounts for the time each parent directly supports the child. The more overnights the non-custodial parent has, the greater the reduction in their payment — but the adjustment is not dollar-for-dollar because fixed costs like housing don't decrease when the child is away.

Below 128 overnights, Ohio generally treats the arrangement as a sole custody situation with standard visitation, and no custody time adjustment is applied to the child support calculation.