Can I deduct Medicare premium payments or enter them to see if it is better to itemize deductions instead of taking the Standard Deduction?

[ScruffyCurmudgeon]

For Tax Year 2018 (due April, 2019):  If you itemize your deductible expenses, then TurboTax will calculate the amount of medical expenses (doctors, hospitals, lab test, crutches etc., dentists, acupuncturist, Rx (prescibed legal) drugs, medical insurance premiums, anything else plus transportation expenses, and using the rule for 2018, included as deductible expense all such costs that are greater than 7.5% of your Adjusted Gross Income (AGI).  So, it is worth considering entering these expenses if you also have other deductions such as state and local taxes, or charitable deductions.   For Tax Year 2019, the starting point is 10% of AGI for medical deductions.

Medicare B premiums are typically automatically deducted from paid Social Security benefits.  They are deductible medical insurance expense and would be reported as deductible in a fashion similar to the premiums for a Medicare Advantage plan or a Medicare Supplement plan to Original Medicare.

The Form SSA-1099 issued to you at the beginning of January by the Social Security Administration will report the total of Medicare B premiums that were deducted from your Social Security benefits.

If you are still employed and have not reached age 70, and have chosen to not yet receive Social Security benefits, then you are billed monthly by CMS (Centers for Medicare and Medicaid - U.S. government) for these premiums and typically pay by check or credit card payable to CMS. Again, these are deductible medical insurance expenses.

Medicare A premiums, which you actually never see in a report, are not deductible, so don't worry about those.

Assuming that you have enrolled, or been enrolled, in Medicare, you also may have chosen to have a Medicare "Medigap" insurance plan to cover deductibles and co-pays (Blue Cross Blue Shield Medex is an example).  These payments are billed monthly or quarterly and you probably pay by check.

Alternatively, instead of a Medigap plan, you may have chosen to enroll in a Medicare Advantage plan, and again these Medicare Plan C premiums are deductible.

Lastly, you may have (wisely) chosen to enroll in a Medicare Plan D Pharmaceutical coverage plan (if you are not in an Advantage plan), and these premium are also deductible.

[Texas Roger]

Yes you can deduct premiums paid for medical insurance which includes the types of insurance described in Scruff_Curmudgeon's thorough answer. There is a relatively high threshold to get any tax benefit from medical expenses. Only the amount of unreimbursed medical expenses in excess of 7.5% of your Adjusted Gross Income can be deducted. Those deductible expenses along with all your other itemized deductions must add up to more than the standard deduction for you to get a tax benefit. TurboTax does the calculation for you after you have entered all your unreimbursed expenses. You won't know the result until you have entered all your income and all your itemized deductions. Many taxpayers who itemized deductions in past years are expected to get a better result from the standard deduction in 2018 since the deduction is now about double what it was last year.