it is asking if and when you became covered by medicare. for the portion of the year you are covered by medicare you are ineligible to contribute to an HSA. if you did you must withdraw the excess contributions before the due date or be subject to penalties. 

for example if medicare started in February 2020, you would only be able to make a pro-rate contribution for January. max for a single person over 55  is $4550. so you could only contribute 1/12 that amount. 

Thanks for that, but I am wondering if this applies when you ONLY have Medicare part A. This covers hospitalization only and does not replace healthcare coverage.

No. Form 8889 is used to report health savings account (HSA) contributions (including those made on your behalf and employer contributions).

You cannot deduct any contributions for any month in which you were enrolled in Medicare. @Mike9241 is correct. Talk to the plan administrator about how to withdraw excess contributions. 

See 2020 Instructions for Form 8889 Health Savings Accounts (HSAs) page 1: 

To be eligible to have contributions made to your HSA, you must be covered under a high deductible health plan (HDHP) and have no other health coverage except certain disregarded coverage.

If you are an eligible individual, anyone can contribute to your HSA.

However, you cannot be enrolled in Medicare or be another person's dependent.

An individual does not fail to be treated as an eligible individual for any period merely because the individual receives hospital care or medical services under any law administered by the Secretary of Veterans Affairs for a service-connected disability.

You must be, or be considered, an eligible individual on the first day of a month to take an HSA deduction for that month.

Last-month rule. If you are an eligible individual on the first day of the last month of your tax year (December 1 for most taxpayers), you are considered to be an eligible individual for the entire year.

@barnettdk1

Ok, thanks.