Because your wife is "covered" by an HDHP, she is allowed to make contributions to an HSA in her own name, even if she is not the owner of the plan. You share the same overall family limit ($8300) but her $1000 catch-up provision is her own. So at the present time, she could contribute up to $83 per month for each month that she is not covered by other insurance that disqualifies her from making HSA contributions.
Once she is "covered" by other insurance, she is not eligible to make HSA contributions in her own name, even if she is also covered by the HDHP. Remember that if she is more than 3 months past her 65th birthday, her Medicare enrollment will be back-dated to the month of her 65th birthday, or backdated 6 months from the date of enrollment if she is more than 6 months past her 65th birthday, and that will change the limit on her contributions.
Your contribution limit is not affected by her status, only your own. If you remain covered by a family HDHP and have no other coverage, you can contribute up to $9300 for 2024. If your workplace switches you to a single HDHP because your spouse is no longer covered, your limit will be reduced accordingly ($691 per month for each month you are enrolled in a family HDHP and $345 per month for each month you are enrolled in a single HDHP).
Remember that whenever you enroll in Medicare, your enrollment will be backdated 6 months, and that will make you ineligible to make HS contributions from that point.
