I am a French citizen, J1 research scholar at a university in the US since 2021. In 2021 and 2023, I benefited from a 2-years tax treaty to pay my income tax in France, and be exempt from income tax in the US. Since the tax treaty ended on Sep 30, 2023, I am now a US resident for tax purposes, but 2023 is a mixed year in term of income tax. This year, I indeed received both a W2 and a 1042-S:
In Turbotax, I am able to add the W2 but not the 1042-S. As a result, Turbotax thinks that my income is only 25% of what I actually earned in 2023. How do I properly declare my situation to Turbotax? What should I do with the 1042-S?
Normally people who fill out 1042S file 1040 NR (non-resident). TurboTax does not support that form.
There are instructions in TurboTax help for reporting 1042S on a 1040 (NOT NR), but I would be careful that you are using the right forms, not doing part in TT and part out.
You can however take the work you have done in TT and use it to guide you in filling out most of the blanks on a paper form. Just realize your final work will need to be on paper, using the precise forms required, with or without professional assistance and/or software.
Disclaimer: I haven't filled out a return like yours, so my input may be inadequate to answer your question.