In general, if you are enrolled in an OGB health insurance plan and become eligible for premium-free Medicare A when retired, OGB requires you to enroll in Medicare Parts A & B. Medicare then becomes your primary coverage and OGB is your secondary coverage and your OGB premiums are reduced.
You must provide OGB with a copy of your Medicare card. Alternatively, if you are not eligible for the premium free Medicare A, please send OGB a letter from Social Security that you are not eligible.
Once enrolled in Medicare Parts A & B, your OGB drug benefit becomes a Medicare Part D plan. Enrollment in any other Medicare Part D plan cancels your OGB coverage.
More information on this topic can be found in this issue of The Beam newsletter.