@Helen123 , your statements are generally correct.
1. Why does not Mark join the thread directly instead of through you ? I am sure he appreciates your help ( since you have lived here in the USA and then moved to Hong Kong ) but .....
2. How did he file his returns for 2022 and 2023 ?
3. Note also that unless his stay in the USA is for a full calendar year and as a resident, he will have to use itemized deduction and that itself ( depending on exact facts and circumstances ) may be a disadvantage.
Is there more I can do for you and/or Mark ?
pk
