West Australian Opposition Leader Mike Nahan has revealed he is still a US citizen because the Internal Revenue Service believes he owes unpaid tax.
Dr Nahan says he came from Michigan to Australia about 40 years ago, became a citizen around 30 years ago and started the process of renouncing his US citizenship shortly after being elected in 2008, but it hasn't been finalised for tax reasons.
"I am a dual national, technically," he told reporters on Tuesday.
"The US government will not allow the renunciation until I resolve the tax issue.
"The Internal Revenue Service in the US is a difficult beast.
"I will continue to pursuing the renunciation of my US citizenship. I hope it's finalised soon."
Legal experts recently said WA parliamentarians applying for or using a foreign passport could be considered to be demonstrating an allegiance to a foreign power under the state's constitution, and that may be grounds for disqualification.
But the state government said that would only be an issue if they did so after they were elected, according to advice from the Solicitor General.
Dr Nahan, who was a Barnett government minister and treasurer, said he only used his Australian passport, did not intend to apply for a US passport and had been advised his dual citizenship did not disqualify him from parliament.
He said he made the admission about the tax bill because his office had previously stated he was not a dual citizen.
