- Original version was called Percent-of-Income and developed in Wisconsin by Jacque van der Gag as a tax on the gross income of obligators in low-income cases.
- Later refined to Percentage-of-Obligator Income, its popularity peaked when the Guidelines first became presumptive in 1989 because of its simplicity.
- Its popularity was short-lived for three reasons:
1. 1984-1987 Guidelines Project did not recommend it
2. Too simple for adjustments like childcare, parenting time and health care premiums
3. Ignored income of custodial parent
- There are currently two variations in use– fixed and varying percentage. With both variations, it ignores income of custodial parent because it assumes that their entire income is spent on children.
- It calculates support as a percentage of non-custodial parent’s income and number of children.
- Eight states use it: Alaska, Arkansas, Mississippi, Nevada, New York, North Dakota, Texas, and Wisconsin
- In the last twenty years, five states switched to Income Shares (Georgia, Illinois)
- Initially, most states used Van der Gaag 1981 as the economic study with this model. Currently, only half of the states use it.
- There is an even number of states using the two income bases (gross vs. net)