Welcome to Just Answer. I am here to help you resolve your tax and finance concerns. Please feel free to ask anytime you need extra help.
They are not refundable as such. The foreign taxes collected by the other nation do, however, entitle your client to claim the foreign tax credit on his/her US tax return. This is a nonrefundable credit that cannot reduce the total income tax due below zero. A point to consider is that, if your client meets the requirements, he/she will be able to exclude the foreign income (up to $91,500). The requirements for both items can be seen at www.irs.gov
Please feel free to ask if you need additional assistance.
Since, the state begins with the Federal taxable income, and since the Federal taxable income has taken the exclusion into account, the state also provides for the exclusion.
Most foreign nations do not offer a refund of taxes to individuals unless, according to the local law, there is an overpayment. The tax treaties in place recognize the sovereignty of other nations and, with that, their right to tax workers earning within their borders.