I’m turning 65 on April 1, 2015. Can I use a health savings account (HSA) for 2015?

Once you enroll in Medicare (April 1, 2015), you are no longer eligible to contribute to an HSA. You can, however, contribute to an HSA for the months prior to this date (assuming you are covered by a high-deductible health plan for this period). Thus, you can contribute for one quarter of the year (and your dollar limit on your contribution is one fourth the annual contribution limit.