In 2026, Colorado child support changes are usually based on a change in circumstances that is substantial and continuing, and the court focuses on updated income and parenting time facts. You typically want recent pay stubs, tax returns, proof of health insurance premiums for the child, and documentation of child care costs if those apply under the guidelines. If parenting time changed, keep calendars, school records, and any written agreements showing when the change occurred. Colorado statutes address modification of support orders and the child support guidelines that drive the recalculation, so the paperwork needs to match those standards. In most situations, the effective date is tied to when you file the motion, so waiting too long can cost you money even if your situation changed earlier. A lawyer can help package the evidence so the court sees a clean before and after comparison that supports the guideline result.