Hi,

I'm a non-US citizen that worked in the US for 3 years as a resident alien prior to moving to back to Europe last year. I will however continue to receive a salary from my previous (US-based) employer for the next 3 years for the work I have previously done (although the employment is now terminated).

My understanding is that I will be a non-resident alien, but will have to pay Federal and Social Security/Medicare since the income is US sourced. State and City taxes I believe are not required as I will not have lived in a US state for any portion of the year.

Is my understanding correct or have I missed something?

Thanks!

Yes, I believe that your understanding IS correct.