HSA Contributions after age 65 while on company-sponsored HDHP

[slw_skater]

I work for a large company and am currently enrolled in an eligible HDHP and contribute to an HSA and my company also contributes.  I am currently age 65 and I do no not collect social security and am not enrolled in Medicare.  Our open enrollment season is coming up for 2026 and I would like to stay in my plan and continue to contribute to an HSA as long as I am legally eligible, but will change plans if that is safer or required to not break any rules.  I plan to retire on 2/28/2027 and go on Medicare and Social Security starting 3/1/2027.

From my research, I should apply for Medicare 3 months in advance of my retirement date, so on 12/1/2026, and there is a 6 month lookback rule from that date for NOT contributing to my HSA.  That would be 6/1/2026. 

Am I correct that my combined personal plus company contribution to my HSA is the equivalent of 5 months of 2026?  So 5/12 of $4400, plus 5/12 of the $1000 catch up contribution?  

Please advise if my understanding is correct or incorrect, as I do not want to get dinged for excess contributions or any other violation of these complex rules.  Is it simply safer to just go on another health care plan at work and not contribute to an HSA at all in 2026?  Thank you.

[Opus 17]

Medicare is effective retroactive to 6 months before you apply (unless you enroll when you turn 65).   If you apply for Medicare 3/1/27, it will be effective retroactive to 9/1/26.   I'm not sure what you are talking about by applying 3 months early, there might be a variation I am not aware of.

The point is, you need to know the Medicare effective date.  That determines your HSA eligibility.  If your Medicare effective date is 6/1/26, then you did correctly calculate your contribution limit for 2026, as 5/12th of $1000 plus 5/12th of $4400 (for single HDHP coverage). 

That is your limit for the year, but it does not matter when during the year the contributions are made.  You can even make contributions after your Medicare start date as long as the total for the year does not go over your limit.  For example, you could make $187.50 per month of payroll contributions for the whole year, instead of $450 per month for 5 months then stopping after 5 months. 

[slw_skater]

Thanks for your reply.  I read on this site that someone should apply for Medicare 3 months before leaving a company.  When To Stop HSA Contributions Before Enrolling in Medicare - Retirement Daily on TheStreet: Finance...

Here's a clip:

Behind the scenes, Medicare Part A has a 6-month retroactive start date. And therefore, contributions to an HSA become ineligible six months before filing the application.

The key word is applying. When coordinating all pieces of one’s Medicare packet, you should apply three months before leaving the company. The Medicare retroactive period starts at the application date, not at the retirement date. 

And now a new question:

In my case, I want to start actually using Medicare on 3/1/27 rather than my company's plan after I retire, so that's why I indicated that I thought my application date would be 12/1/26 (based on the site above), with the 6-month look-back to 6/1/26.

If Medicare becomes effective 6 months before the application date, then does that mean if I apply on 3/1/27, I'm technically covered all the way back to 9/1/26 (and could go to doctors and Medicare would pay starting then)?  So there's not really any reason to apply earlier?  If I apply on 3/1/27 with coverage effective back to 9/1/26, then could my contribution limit would be 8 months out of 12, rather than 5 months out of 12?

Thanks again.  This topic is super complicated!

[Opus 17]

---

@slw_skater wrote:

And now a new question:

In my case, I want to start actually using Medicare on 3/1/27 rather than my company's plan after I retire, so that's why I indicated that I thought my application date would be 12/1/26 (based on the site above), with the 6-month look-back to 6/1/26.

If Medicare becomes effective 6 months before the application date, then does that mean if I apply on 3/1/27, I'm technically covered all the way back to 9/1/26 (and could go to doctors and Medicare would pay starting then)?  So there's not really any reason to apply earlier?  If I apply on 3/1/27 with coverage effective back to 9/1/26, then could my contribution limit would be 8 months out of 12, rather than 5 months out of 12?

Thanks again.  This topic is super complicated!

---

That is beyond my competency.  You may want to talk to some kind of elder law financial planner.

And in any case, "effective" might not be the same as "not paying".  If you don't get your Medicare card until June, you might have to pay full price for procedures before that date and then get reimbursed, or you might have to work out a deal with the doctor to not pay up front because they will eventually get the money.

In other words, it may be more for convenience reasons that you want that medicare card on day 1.

But, speak to an expert.  I understand the taxes (more or less) but not the rest. 

[dmertz]

I believe that the lookback is 6 months or to the month that you reached age 65, whichever is later.

https://www.medicare.gov/basics/get-started-with-medicare/sign-up/when-does-medicare-coverage-start

[Opus 17]

---

@dmertz wrote:

I believe that the lookback is 6 months or to the month that you reached age 65, whichever is later.

https://www.medicare.gov/basics/get-started-with-medicare/sign-up/when-does-medicare-coverage-start

---

Right.  This taxpayer is planning to enroll at 67 or 68.  The exact rule, as I understand it, is that if you enroll during the standard enrollment period (which is from 3 months before to 3 months after the 65th birthday, the enrollment is effective on the first day of the month in which you turn 65.  If your birthday is the first, your enrollment is effective the first day of the previous month.   If you enroll after the standard enrollment period, the lookback period is 6 months, but never earlier than first day of the month in which you turn 65.