@kim_hung_lo
I'm going to ask for help, because there is one part of the spousal rule that I am not sure about. If one spouse is covered by a family HDHP, then both spouses are treated as being covered. But, that only applies as long as "both spouses are eligible individuals." Eligible means you are covered under an HDHP, have no disqualifying coverage, aren't on medicare, and aren't someone's dependent.
@dmertz
Here, I may have been mistaken above about your wife being treated as having a family HDHP if you have one. For the month of December, she is not covered by your plan, if you proceed as described, so she is not an eligible individual.
Assuming that your wife is not covered by an HDHP on December 1, 2024, then her limit for 2024 is $3804 for regular contributions and $916 for the catch-up, for a total of $4720. That's 11/12ths of the limit, and assumes she had coverage on November 1. Eligibility is determined on the first day of each month.) If she was terminated before 11/1 and not covered on 11/1, then her annual limit would be 10/12th the usual amount.
She can contribute up to her limit for the year, and it doesn't matter when in the year the contribution is made, (even after the termination) as long as she doesn't go over her limit. If she makes out of pocket contributions, they become a tax deduction on your tax return.
If she contributes up to her limit of $3804 plus $916, then your limit is $4496 plus $1000.
If she takes COBRA, and it is a qualifying HDHP, then her limit would be $4150 plus $1000, and she can make those contributions out of pocket and take a tax deduction. Your combined overall family limit is still $8300, and your limit would be ($8300 minus wife's contribution) plus $1000.
