I now see the problem (thanks for the description). The problem is that you can't withdraw the excess so TT assumes that you had an HDHP coverage to contribute under. Apparently, it doesn't allow for the situation of there being no coverage...hmmmn, at this point (late in tax season) I am not sure what it was supposed to do, but to move you along, just click the Self box. It won't change your tax at all (you've already fixed that when you said that you were on Medicare the whole year), and hopefully SmartCheck will be happy and let you finish.
I am sorry for the confusion, but checking that box in this case will be fine for the IRS...
