The economy has lead many people to revisit their court ordered support obligations. In NY the number of request is jamming the court calendars. http://www.nytimes.com/2009/03/29/nyregion...ort.html?ref=us Nonetheless it is absolutely essential that if need be that a modification be sought.
The court has NO power to retroactively modify an order to a date earlier than the request is made. So regardless of your income or circumstances if an order is in existence you will have to pay it plus judgment interest of 10% per annum on the unpaid amount. This amount will stay on the books forever until paid in full plus the interest. Also the arrears can lead to contempt charges and jail, loss of license privileges (including professional licenses such as those required to practice medicine, law, building contractor, architect etc) and loss of the privilege of travel outside of the country as a hold on any issuance of a passport can but put in place.
In California you can make an easy assessment regarding a potential modification by going to the state computer and doing your own guideline calculation at www.childsup.ca.gov/calculator