The tax withholding rate for royalties paid to non-US payees is 30%. If the country where you claim to be a resident for purposes of that country’s income tax has an income tax treaty with the United States, you can claim a reduced rate of withholding by completing the tax interview with your valid tax identity.
For more information regarding U.S. tax withholding rules for royalty payments made to non-U.S. persons, see IRS Publication 515 for details. http://www.irs.gov/pub/irs-pdf/p515.pdf
For more information on countries which have existing tax treaties with the United States, see pages 36-37 of IRS Publication 901. http://www.irs.gov/pub/irs-pdf/p901.pdf