No, but you can try to get present child support lowered by telling tecourt what happened. It will be a uphill battle. Try negotiating with he Custodial Parent.
My name is Stephen R. Cohen and I have practiced over 38 years and can be reached at 213-819-1171. I practiced mainly in Los Angeles and Orange County, California. I am not seeking clients from existing relationships with other attorneys, and give only limited advise over the phone (the phone is primarily used to set appointments), these services do not create an attorney client relationship. I apologize for mispelling< as I am a lousy typist, My answers may offend as I do not believe in pulling punches or sugar coating the truth. Further regarding courts in other states my opinions are largely based on logic and what I think is the modern trend which is to consider the needs of the child.
As for your current child support amount (per the existing court order), if that amount is incorrect based on either your income, the other parents income, or the parenting plan, then you should file a child support modification motion ASAP. Any modification of support is only retroactive to the date you file the motion with the court.
As for arrears, there are some VERY LIMITED circumstances in which arrears may be reduced depending on the facts in your case. You should consult with a local family law lawyer (one that is experienced with this type of issue) to see whether the facts and circumstances in your matter warrant a reduction of arrears.
In the meantime, here's a link to a list from a family law lawyer in LA regarding ways to reduce arrears: http://www.childsupportla.com/servicesback.htm