Thanks, I'm glad we got that sorted out. The crucial element, then, is to sign up for Medicare within the six-month window (three months before and three months after my effective date). The six-month lookback is a concern only if I delay signing up. Thus Medicare's statement about the six-month rule, which is what alarmed me, is basically overkill or poorly stated.
I raised my question because Medicare's statement seemed to override the IRS's example and caused me to wonder what the IRS really requires. Some of the confusion in our discussion about it was probably caused by my mixing two different issues: what the IRS requires, and what I plan to do.
As I see it, for purely practical reasons I'd simplify my life if I sign up for Medicare before July 1. My reason for making the HSA contribution soon is likewise merely logistical: get the money into the HSA, exhaust it as the source to pay my medical bills, and then switch to credit cards. Doing things that way is my preference and will satisfy the IRS. It's the K.I.S.S. principle: Keep It Simple and Straightforward.
