To report any changes to enrollment of Medicare Part B for a group/entity or individual, you must use the appropriate CMS 855 form. Changes will not be accepted on letterhead. When reporting changes of information, check and complete the appropriate section(s) where the change is being reported. All changes must be reported to the carrier within 90 days of the effective date of the change. Submitting changes to the information reported in your original enrollment application immediately will ensure accuracy as well as avoid unnecessary delays. A delay in receiving Medicare payments can be avoided by submitting the appropriate CMS form in a timely manner.