INS-MEDICARE OPEN ENROLLMENT. Amends the Illinois Insurance Code. Provides that a Medicare supplement policyholder is entitled to an annual open enrollment period lasting 60 days or more, commencing with the individual’s birthday, during which time that person may purchase any Medicare supplement policy that offers benefits equal to or lesser than those provided by the previous coverage. Provides that, during the open enrollment period, an issuer of a Medicare supplement policy shall not deny or condition the issuance or effectiveness of Medicare supplemental coverage, nor discriminate in the pricing of coverage, because of health status, claims experience, receipt of health care, or a medical condition of the individual if, at the time of the open enrollment period, the individual is covered under another Medicare supplement policy or contract. Requires an issuer to notify a policyholder of his or her rights under this subsection at least 30 days and no more than 60 days before the beginning of the open enrollment period, and on any notice related to a benefit modification or premium adjustment.