Assuming a non-US citizen does not pass the substantial presence test and is classified as a non-resident alien for tax purposes, what restrictions/limitations may prevent them from contributing to a 401(k) and/or IRA? Please assume the individual maintains a US work visa and is seconded overseas while still being paid by the US entity, and they return to the US for short periods of time throughout the year.
I understand the individual must have US sourced income, but is there any firm guidance on how much? Is 1 day working in the US sufficient to classify the individual as having US sourced income and allow contribution to a 401(k)? Any special considerations if contributing as Roth vs. Traditional? Is it possible/common for a plan to specifically exclude non-resident aliens from contributing at all? Are the restrictions different for an IRA?
