Part B Late Enrollment Penalty

I have a prospect turning 65 in June. He is 100% disabled and goes to the VA for most of his healthcare. He is dissatisfied with the care he is receiving at the VA. He never took out the Part B when he became eligible for Medicare 13 years ago because he always assumed he would get all of his Medical care at the VA. He now wants to get a Med Supp but I told him he will have to pay a substantial penalty for late enrollment for the Part B. He was upset to learn of that fact and will be checking with Social Security to verify what I told him. My question is did I tell him correctly he will

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