The Medicare Open Enrollment Period (OEP) runs from Oct. 15 to Dec. 7 every year. Anyone who already has Medicare coverage of any kind can make changes to their coverage for the upcoming year. Medicare Advantage Open Enrollment runs from Jan. 1 to March 31 every year. Only people who already have a Medicare Advantage plan can change during this time. Dual Special Needs Plans (D-SNPs) are a type of Medicare Advantage plan so the same enrollment periods apply. You can apply for Medicaid at any time throughout the year. There are no enrollment periods for Medicaid or CHIP (the Children’s Health Insurance Program). Learn more about Medicare enrollment periods.