@Japtrupusz , since you are saying the taxpayer ( whom has already renounced/ abandoned her Green Card ), her US world tax liability ceases from the day her abandonment has been accepted ( often the day she left the country). That is for the period till the end of the year from this date she would be Non-Resident Alien, subject US taxes on ONLY US sourced income. Note that passive income like interest income is taxed at a flat 30% for a Non-Resident Alien.
If she had foreign bank/ financial account ONLY post abandonment of Resident status, there is NO requirement to file FBAR ( FinCen 114 ) or FATCA 8938.
Note also that ( i did point this out earlier to your other post ) that because she is a dual status alien ( not having passed the Substantial Presence Test for the year ), she file form 1040 for the past part of the year ( Resident portion and 1040-NR for the Non-Resident portion of the year. This also means that she would be restricted to using itemized deduction.
Whether Poland will tax ( double tax ) the interest income would be under their tax law. Perhaps a quick look at US-Poland tax treaty will answer that question. I am pretty certain though that if she is considered a resident of Poland , then Poland would have the right to tax the income. Amelioration of this double taxation needs to be discussed with a local tax professional and /or tax department. I am pretty sure this has happened before .
Hope this answers your questions(s) Is there more one of us can do for you ?
