RE HSA Contributions, Retirement and Social Security Medicare filing in 2020.

Over 55, planning retirement month in 2020 but still actively employed with High Deductible Health care coverage for the family so the annual max into HSA is 8,100.  I have the option of deferring a lump sum payment in February into my HSA. If I'm understanding Social Security Medicare filing correctly with it's 6 month retroactive provision, a February contribution means the earliest filing date would be in September with a monthly proration of the annual HSA limit determining the maximum amount of my February lump sum payment. Correct ?

Also I note congress was discussing a change to the HSA/Medicare rule last year under the Senior Health Care bill but have not been able to find the current status or any changes for 2020 on the conflict between HSA and Medicare?

"If I'm understanding Social Security Medicare filing correctly with it's 6 month retroactive provision, a February contribution means the earliest filing date would be in September with a monthly proration of the annual HSA limit determining the maximum amount of my February lump sum payment. Correct ?"

You are not eligible to contribute for any month that you are covered by Medicare.   If for some reason you wanted to contribute to an HSA the entire $8,100 family limit for 2020 and you were at least age 65 in 2020 you would have to wait long enough to sign up for Medicare such that your Medicare coverage would not be effective before the end of 2020.  If your Medicare coverage instead begins in 2020 you would be able to contributed to the HSA only the prorated amount of the family limit and catch-up for the months that you were not covered by Medicare.

http://www.wolterskluwerfs.com/article/health-savings-accounts-how-medicare-coverage-affects-regular...