Proving income abroad was not for services rendered in ROC?

The tax office has raised concerns that my US income from 2001 and 2002 may be subject to ROC taxes. This income was from a US source, was paid in the US, and was for work done in the US. However, since I was considered an ROC resident for those years, they say I need to ‘prove’ that the income was not for work performed here. I was told that I need a CPA to attest to that, but it was fairly confusing exactly what they needed. Anyone gone through this before that have any suggestions? Thanks!

how did they learn about this income J?

They asked why I didn’t file an ROC tax form for those years, and I told them. (Yeah, I know, not so smart, eh?) It was just the people at the information desk they set up, so I’m not sure if there was an official notation of what was discussed. However, I would still like to know if anyone else in this situation used as ‘proof’ to satisfy this query in case this is raised as an issue in the future.