@Illia ,
a few questions first before I opine:
(a) Which country are they from and are they both resident and citizen of that country ?
(b) When did they enter the US with J visa and exact date when they left the UJSA ?
(c) Did they file any forms with the IRS or Immigration stating that they are leaving the US or was it just their employment/research visa terminated ?
(d) Should I assume that their ONLY financial connection to US post departure is passive income -- bank interest ? Or is there more and substantial connection ?
Generally , I would try return with two different scenario ( assuming there are no other contravening facts :(
1. AS a dual status --- Jan 01 2025 through Sept. 30th Sept -- Resident and being taxed on world income, itemized deduction and 1040-NR for earnings ( US sourced ONLY ) for the last quarter of the year 2025
2. AS a resident for the whole year, form 1040, taxed on world income, standard deduction and allowing foreign earnings to be taxed by the USA, foreign tax credit for the taxes paid to home country. This is assuming that there is no contravening facts .
I will circle back once I hear from you --yes ?
