Net income can be higher than gross income if various credits, including especially the Earned Income Credit, are more than the tax otherwise payable.
This is a very frequent occurrence with lower income taxpayers who have children.
In Florida, we have provided an option to have the software ignore those credits for the purposes of calculating income for child support.
To do that, click Support Data > Wages, and Filing Status, and then one of the checkboxes shown below.
