The answer given by Ayatollah Mahdi Hadavi Tehrani is as follows:
1. You must abide by the rules of the country in which you are living except for when the rules may be opposed to Islamic Shari'ah.
2. If evading tax may result in defamation of Muslims, it would be absolutely forbidden; otherwise, it is also necessary to abide by the law of the country in which you are living as a legal citizen except for when the laws may be opposed to Islamic Shari'ah.