@yashK
Once a person has money in an HSA, they may spend it at any time for qualified medical expenses for the account holder, their spouse, or their dependents, even if they are no longer eligible to contribute. So, yes, your spouse may request reimbursement from her old HSA for any current medical expenses. They do not have to wait until next year if you have eligible expenses now.
If you enroll in a family HSA-eligible HDHP now that includes your spouse, then you may open an HSA and make tax free contributions up to the family limit. It does not matter if your spouse has overlapping non-HSA eligible insurance, unless that insurance covers you as a secondary beneficiary. If you have any secondary medical coverage, and that includes a spouse’s FSA (but not HSA) then you are not eligible to make tax-free contributions as long as that secondary coverage exists.
If you are eligible to contribute to an HSA on December 1, then you could contribute up to the annual family maximum of $7300 for the calendar year 2022, by relying on the “last month rule.” The last month rule says that if you are eligible on December 1, you may make a full years’ worth of contributions, as long as you maintain full eligibility for the entire next year. (If you use the last month rule to make a large contribution for 2022 and then you lose your HSA eligibility in 2023, your 2022 contributions will retroactively be determined excess contributions and you will be subject to a penalty.) You have until April 15, 2023, to make tax deductible contribution for 2022. If you have some payroll contributions in 2022 but not enough to fill the maximum, you can make extra out-of-pocket contributions from your checking account and then take a tax deduction on your tax return. Make sure you tell the HSA bank that the deposit is for the 2022 tax year instead of the 2023 tax year, this will be a selection on the website when you make the deposit.
