You got it 99% correct.
1. Beginning on 7/1/22, your husband was ineligible to make contributions. His eligible limit for 2022 was $1825, assuming he was enrolled in single HDHP coverage. ($304.16 per eligible month)
2. If your FSA ends on 6/30/23, and you do not re-enroll in the FSA**, and you have no funds to spend in a grace period, then your husband is eligible to make contributions beginning 7/1/23. If he remains eligible for all of 2023 and plans to remain eligible for all of 2024, he can use the "last month rule" to contribute the 2023 maximum of $3850 as if he were eligible all year. (Note that even if you had funds available to use in a grace period, and he did not technically become eligible until 9/1/23 or 10/1/23, he can still use the last month rule to contribute the maximum amount.)
**You can enroll in a "limited purpose FSA" if your employer offers it. A limited purpose FSA only covers certain items that do not conflict with the HSA rules, mainly dental and vision care. If you are expecting dental work, or wear glasses or contacts, you might look into using a limited purpose FSA to pay for those things. The full list of items that can be paid from a limited purpose FSA is found in publication 969.
https://www.irs.gov/publications/p969#en_US_2022_publink1000204039
3. Your husband has $1825 of excess contributions for 2022. There are 3 ways of dealing with this, one of which has really high taxes so I won't discuss that here. The two more sensible options are:
A. Contact the HSA bank and remove the $1825 excess contribution along with any earnings. File an amended 2022 return (not 2023-- the return you filed in April 2023 was for tax year 2022) to report that he was ineligible for 6 months. Turbotax will add back the $1825 to his taxable income. You will also report that you removed the excess before the deadline. You will not be assessed a penalty. You must file this amended return by mail and write “Filed pursuant to section 301.9100-2” on the top of the first page, and include a written explanation of the late withdrawal. Any income from the excess will be taxable income in 2023, the year you withdrew it. (This amended return must be filed before October 18, 2023.)
B. Leave the excess in the HSA. File an amended 2022 return to report that he was ineligible for 6 months. Turbotax will add back the $1825 to his taxable income. Because you have not removed the excess, you will also be assessed a 6% penalty. You can e-file this amended return. Then, stop your husband's HSA contributions for 2023 by June 30, or adjust them down, so his total 2023 contributions do not exceed $2025. Since the 2023 limit is $3850, he can contribute up to $2025, and the excess $1825 will be applied to the 2023 limit (making a total of $3850). In other words, he can "use up" the excess by contributing less than the maximum for 2023. Your 2023 tax return will show no excess contribution remaining in the account and no further penalties.
If for some reason your husband becomes ineligible in 2024, after relying on the last month rule in 2023, he would owe a penalty on his 2024 return. So if you are planning a job change or insurance change in 2024, you may want to re-think using the last month rule in 2023.
