In Illinois, child support is calculated based on the non-custodial parent's net income. Net income is calculated by taking gross income less all applicable deductions: taxes, union dues, uniform dues, health insurance premiums for coverage for the minor children, mandatory pension contributions. Child support for one (1) child is 20% of the non-custodial parent's net income; two (2) children 25%; three (3) children 32%; and four (4) children 40%. The custodial parent's income is not a factor in the calculation. Deviations from the statutory guidelines are based on a case by case basis. Some instances of deviating fom the above percentages are: when the non-custodial parent has shared physical custody, the non-custodial parent has more time with the children than the statutory standard visitation; the non-custodial parent is supporting other children through prior child support order(s).