SPRINGFIELD — State Senator Michael E. Hastings is backing legislation to further modernize Illinois child support law, building on the income-shares model he helped enact in 2016.

“Too often families spend thousands of dollars fighting over formulas instead of focusing on their children,” said Hastings (D-Frankfort). “This is about fairness, transparency and lowering conflict so parents can prioritize stability and co-parenting.”

Senate Bill 3524 would amend the Illinois Marriage and Dissolution of Marriage Act to change how child support is calculated in shared parenting cases. The bill lowers the threshold for applying the shared-care formula from 146 overnights per year to 110, expanding eligibility for families in which both parents play a significant caregiving role.

The proposal would also allows courts, or parents by agreement, to count certain periods of substantial daytime care as ‘overnight equivalents’ when a child is in a parent’s physical care and under direct supervision, even if the child does not sleep there. Supporters say the change better reflects the realities of shift workers, nontraditional schedules and modern co-parenting arrangements. Hastings said the measure is intended to make the system more equitable and less likely to fuel costly disputes.

Illinois moved to the income-shares model in 2016, replacing the state’s former percentage-of-income approach. Under that framework, child support is based on the combined net incomes of both parents, the child’s needs and each parent’s proportionate share of responsibility.

The bill would refine that model by applying the shared-care calculation to more families. Under the bill, courts would begin with the basic child support obligation, multiply it by 1.5 to account for duplicated household costs across two homes, assign each parent’s share based on income, adjust for the amount of parenting time exercised by the other parent, and offset the two figures so the higher-paying parent pays the difference.

The bill also creates a statutory table for cases falling between the previous 146-overnight benchmark and the new 110-overnight threshold. Any resulting obligation would be capped so it does not exceed the amount required under the basic guidelines. Additional provisions in the legislation create a rebuttable presumption that parents incarcerated for more than 180 days are unable to pay child support, and a rebuttable presumption that low-income obligors at or below 100% of the federal poverty level for a single person should pay a minimum of $40 per month per child.

Supporters say the measure would better align the law with the way many families actually parent, while reducing litigation over rigid overnight counts and technical formula disputes.

Senate Bill 3524 passed the full Senate and now heads to the House for further consideration.