How can a support agreementbe modified?

Changed circumstances such as a change in income of one of the parties would be a basis for requesting a modification of spousal support.  Your husband should go to the court where the divorce case was filed and obtain court forms for an Order To Show Cause (OSC) for modification of spousal support.  The court forms should include an Application for Order and Supporting Declaration.  Your husband should complete the forms, file them with the court with a proof of service.  When the documents are filed with the court, the court will set a date for the hearing on this issue.  Your husband will need to have the forms served on his ex-wife.  This can be done by mail by attaching a proof of service to the forms.  The proof of service just verifies the date the forms were mailed to the opposing party.  The court has forms for proof of service or your husband can write his own proof of service.  The proof of service says that On_____(date) the attached documents were sent via first class mail to_______ (name of ex-wife) and her address.  The proof of service should be dated and signed under penalty of perjury and the person signing the proof of service should be at least 18 years old.  The date on the proof of service should be the same date the documents are filed with the court.