Yes, Medicare part A disqualifies you from contributing to an IRA HSA.
[Edited, I meant to say Medicare disqualifies you from contributing to an HSA, got my wires crossed.]
To be eligible to contribute to an HSA, you must be covered by a qualifying HDHP and have no other medical coverage. Medicare counts as "other coverage" and disqualifies you from contributing starting on the date your medicare coverage starts. For example, if you were enrolled in Medicare as of June 1, 2022, then you have 5 months of HSA eligibility. Turbotax will walk you through month by month to determine your eligibility. If you were enrolled in Medicare the entire year, then you are totally ineligible to make HSA contributions.
