It is the duty of both parents to financially support their children until they reach the age of 18, and are graduated from high school, or until they reach the age of 19, whichever occurs first. The actual amount of child support is normally calculated pursuant to an algebraic formula provided in the Family Code (Section 4055). Child support calculated by the algebraic formula is called 'guideline' child support. Guideline child support is presumed to be correct unless the family law judge determines that there are extenuating circumstances justifying the judge to make a different child support order.
Although calculated by an algebraic formula, determining the correct child support amount can nevertheless be difficult. For example, on occasion, to avoid paying child support one parent might under-report his or her income. When a parent is self-employed, and is running his/her own business, he or she can control what his/her income looks like, so in such a case it would be necessary to review business documents to ascertain what money is truly available for support purposes. As another example, when one parent is not working to his or her full capacity, the judge can base support on that parent's 'earning capacity' rather than actual earnings. Proving that parent's earning capacity may require a review of that parent's work history and educational background, and determining what jobs are available for that parent at a given time.
