Washington Modification of Child Support — Agreed is a way for parents in the state of Washington to modify child support orders without the need for a court hearing. This type of modification is used when both parents agree on the terms of the modification and can be done without involving a lawyer or the court. The modification must be in writing and signed by both parents and filed with the court. There are two types of Washington Modification of Child Support — Agreed: 1. Interim Modification: This is used when both parents agree to modify the existing child support order for up to six months. 2. Permanent Modification: This is used when both parents agree to modify the existing child support order for more than six months.