what will happen in court for child support?

If you paid your arrears plus $400 extra you will not go to jail.  Bring your proof of payment to court and show the judge.  You only go to jail for not paying when you have the ability to pay, ie directly ignoring a court order to pay when you could have. In your case, if you lost your job, you should file a Supplemental Petition for Modification of Child Support, and an amended financial affidavit.  If the state DOR is involved it is difficult to modify because you must serve the individual petitioner not just the DOR.  The DOR wont reveal the address of the individual petitioner and this can put you in a difficult position trying to serve someone that you don't have an address for. If you are out of work, you should be prepared to show the court where you have been applying for jobs, including the name and address of the employer, and person you spoke with. Normally you are expected to conduct a diligent job search and provide proof that you are trying to find a job if you are claiming to be unemployed as a defense to paying child support.