I am a researcher on J1 exchange visa residing in the USA since 22nd Mar 2012. For Tax year 2012 I paid my entire tax liability (by filing form 1040-NR) but now I know that there is a tax treaty between India and US (article 22 of IRS pub 901) according to which I do not have to pay Federal taxes for a period of 2 years starting 22-Mar-2012. What forms do I have to fill now to claim my tax money back? I am leaving USA on 20-Mar-2014. Grateful for any answers or references.