@CindyKR
First of all, you need to understand that once you have money in an HSA, you can keep it and spend it for any qualified medical expenses even if you are no longer eligible to make a new contributions.
Generally speaking, Medicare becomes active on the first day of the month in which a person turns 65. If they turn 65 on the first day of the month exactly, then Medicare becomes active the first day of the previous month. If your husband‘s Medicare becomes active on December 1, 2021, then he is no longer eligible to make HSA contributions. His contribution limit is $8200 times 11/12 equals $7516. This represents 11/12 of his family maximum of $7200, +11/12 of his individual catch-up contribution of $1000. You do not want to over contribute. You must not over contribute for 2021, and he must not continue to make contributions for 2022.
If your husband continues to contribute the $1700, in order to get the free $1700 match, you have to remember to withdraw the entire $3400 as an excess contribution (prior to the filing deadline each year) and pay income tax on it. Essentially, you are jumping through hoops to get an extra $1700 from the employer. If you forget to make the withdrawal, you will pay income tax plus a penalty and the excess amount that remains in the account will accrue a penalty every year until the account balance is spent down to zero. I would not recommend this as a backdoor way of getting a $1700 raise, I think it has more risks than you appreciate.
Turning to you as an individual, you are also allowed to contribute to an HSA if you are covered by an HDHP, even if you are not the person whose name is on the policy. Your contribution limit if you are covered by a family HDHP is also $7200 plus $1000 catch-up if you are age 55 or older. The $7200 must be divided between you and your spouse and you cannot go over a combined maximum of $7200, while the $1000 catch-up provision can only be contributed to an HSA in your own name.
Let’s assume your husband allows his Medicare to activate but also remains on the company HDHP. He can’t contribute to an HSA in his name any longer, but you can contribute to an HSA in your name. If your husband has maximized his HSA contributions for 2021 at $7516, you can still contribute $1600 to your HSA. That represents 1/12 of the $7200 family limit plus your $1000 catch-up contribution. For 2022, you could contribute up to $8300 to an HSA in your name, as long as you continue to be covered by your spouse’s HDHP.
