Medicare & HSA - Delaying Medicare (and SS benefits) signup 6 months after ending job (after age 65)

[FitWit]

If I'm over 65 1/2, Can I simply Delay Medicare (and SS benefits) signup for 6 months after losing job and stopping HSA contributions so I won't have any excess HSA contributions?

I have read many time to stop HSA contribution 6 months prior to ending my job followed by Medicare signup.

I have also read how to calculate excess HSA contributions that need to be returned if I don't stop HSA contributions 6 months before ending employment.

But what if I want to maximize my HSA contributions and not return any so I simply delay signing up for Medicare and starting Social Security benefits for 6 months after I stop employment?  I can't seem to find anything about this specific case.  What, if any, are the downsides to doing this?

I realize that I will need to get some other health insurance coverage during those 6 months. But, as I understand it, I have 8 months to signup for Medicare Parts A & B after my employment ends, so it seems I would be fine to wait 6 months before doing so and then I won't need to return any excess HSA contributions.  I appreciate any feedback on this if I am missing something or misunderstanding.  Thank you.

[MarilynG1]

Delaying Medicare enrollment after age 65, especially for Part B, can lead to late enrollment penalties, which increase your monthly premium for as long as you have Part B coverage. However, if you have creditable coverage through an employer or other source, you may be able to delay enrollment without penalty, as you mention. 

You may have heard that Medicare will back-date your application, so you're worried about crossover with your HDHP/HSA and Excess Contributions. Medicare starts either on the first of your 65th birthday month, or on the 1st of the previous month if your birthday is on the first of the month, or if you sign up within 6 months of turning 65, the start date is set back to the 1st of your birthday month.  You might want to verify with Medicare on this for your individual situation.

Here's more discussion on HSA and Medicare you may find helpful.

@FitWit 

[FitWit]

In my case, I continued with my employer health coverage beyond age 65 and have 8 months to sign up for Medicare now that my employment and coverage has ended..  I wanted to keep as much of my HSA contributions as possible.  

However, when I recently discovered that COBRA coverage would only pay as a secondary insurance whether or not I have signed up for Medicare, since I am Medicare eligible, I didn't want to risk paying high out of pocket charges (equivalent to what Medicare would have covered) for the next 6 months. That's when I gave up on the my plan to delay Medicare signup for 6 months, and did the Return of Excess for my HSA.  I was surprised how long it took me to learn this about COBRA coverage when you are Medicare eligible.