I didn't sign up for Medicare Part B or a drug plan when I turned 65. What is the penalty?

A late penalty is added to your monthly premium. It is not a one-time fee. Medicare.gov says most people pay it for life [1]. For Part B, you pay an extra 10% for each year you could have signed up but did not [1].

Waiting two full years means a 20% penalty on top of the standard premium, which is $202.90 in 2026 [1]. For Part D, you pay an extra 1% for each month you went without creditable drug coverage [1]. This applies if you didn't join a Medicare drug plan when you first got Medicare and then went 63 days or more without creditable drug coverage [1]. You usually owe no Part B penalty if you qualify for a Special Enrollment Period [1].

Open Medicare.gov, Avoid late enrollment penalties, at https://www.medicare.gov/basics/costs/medicare-costs/avoid-penalties and read the part quoted above. Your own plan or policy papers hold details these sources do not give: "Don't know yet" for your case.