How much of the medical insurance premiums are deductible?
Medical Insurance payments are subject to the 7.5% Adjusted Gross Income limitation rules. That is, they are only deductible to the extent that they exceed the 7.5% AGI amount.
Your filing status does not make a difference as far as the 7.5% AGI limit is concerned. Unfortunately, there are no exceptions for retiree's or taxpayers who have reached age 65.
I would recommend that you keep an excellent record of all your medical and dental out of pocket expenses along with hospital expenses and prescription expenses. These would then be combined with the medical insurance premiums paid, and it may than be possible to exceed the 7.5% AGI limit.