Publication 597, Information on the United States - Canada Income Tax Treaty
This publication provides information on the income tax treaty between the United States and Canada. It discusses a number of treaty provisions that often apply to U.S. citizens or residents who may be liable for Canadian tax.
Publication 901, U.S. Tax Treaties
This publication will tell you whether a tax treaty between the United States and a particular country offers a reduced rate of, or possibly a complete exemption from, U.S. income tax for residents of that particular country.