Mr X lives in country Y and pays tax on the annual accretions in the plan for 20 years, Mr X is transferred to the US to work. Does his US tax basis include those annual accretions he paid tax on. Logic says that it does, but I cannot find anything on point that states that. Does anyone know of a citation I can reference to validate this point? Thank you

This seems to be a homework question.

Regardless, this is often determined by the tax treaty between the country.

Oh yes-I've been doing lots of homework and cannot come up with anything right on point. Thanks for getting back to me so quickly