Pennsylvania has a complex body of law that requires that separated parents pay child support. The laws involved include statutes passed by the Pennsylvania legislature, rules established by the Pennsylvania Supreme Court, and a set of economic guidelines written and regularly revised by a committee appointed to the task by the Pennsylvania Supreme Court, as well as, a significant body of case law regarding how such rules are to be implemented.

A parent's income is usually calculated from at least a six-month average of the party's income. Bonuses and overtime are included if they regularly occur. All of a parent's financial resources, which can include potential earning capacity, income, and income producing property, must be considered in fixing a support obligation. Wages, inheritances, lottery winnings, second jobs, undistributed profit in a parent's business, and all other sources of income or assets can be considered in the analysis.

"Perks" of employment such as automobile expenses, travel, entertainment, transportation, and insurance benefits can be "added back" into a party's income for purposes of establishing a support order. Additionally, non-mandatory retirement contributions are added back to a parent's income for support purposes as well.

This is because most 401(k) contributions are discretionary and the employee can borrow against the plan, the contributions are considered income. However, mandatory contributions to pensions or retirement plans are not included in income calculations in child support cases. Vested stock options generally are reportable on W-2's when exercised and will constitute income for support purposes.

Generally, the value of employer-paid health insurance does not constitute additional income. Less clear is how to treat "flex credits", given as health insurance benefits by some employers. With flex credits, employers pay employees a monthly benefit that each employee can then "spend" on an array of benefits, including medical, dental, eye care, disability, and/or life insurance. In a case involving a mother who received flex credits from her employer for health insurance, the Pennsylvania court held that the money that the mother received for flex credits should not be considered income, even though it was reported with her gross pay on her paystubs. Instead, the court ruled that only the net amount remaining to a parent after the parent spends flex credits should be treated as income available for support.

Such flex credits can also be considered in reviewing whether a parent has paid their required out-of-pocket expenses related to unreimbursed medical expenses for children.