I am a UK scientist, and came to the USA to do a 2 year postdoc. I reclaimed my USA federal income tax under tax treaty article 20A. I did this using forms 1040NR-EZ and 8233.

However, we got a new grant from NSF that has allowed me to stay on for a few more months, so I have lost my treaty benefit, and have to retroactively pay tax over 2 years.

How do I do this, and how long do I have to do it in?

Do I have to pay US taxes on my UK bank account interest for the past two years?

I am guessing that I need to submit form 1040X, with a schedule B: is that correct?

thanks!

There is no time limt to amending the two tax returns to retroactively pay the taxes, but the sooner you do it, the less you will pay in interest charges.

You need to file Form 1040X and attach a amended Form 1040NR-EZ.

You will befiling as a non-resident alien, so NO tax is due on the U.K. bank account interest.

Thanks, this is very helpful!

I am not sure that I am a non-resident, as I seem to pass the "substantial presence test". Can I be a non-resident on the basis that I have closer ties to the UK than the USA? I am on an H1B visa.

The H-1B visa sheds a completely different light on this matter.

The H-1B visa is a work visa; most post-doc researchers arrived under a J-1 visa.

If you were H-1B since your initial arrival in country, then you filed your initial return incorrectly when you claimed the treay benefit under Article 20A. At best, you would file as a non-resident or dual-status alien the first year, then as a resident alien for each full successive year until the year you left, at which time you probably would file as a dual-status alien.