Only under limited circumstances can a Canadian take a deduction for a contribution to a U.S. charity. There is currently a Canada/US treaty that provides for deductibility for Canadians making contributions to U.S.-based organizations. In general, a Canadian may take a deduction on their Canadian income tax return for a contribution to a U.S. charity only if they have U.S. source income, and only up to 75% of that U.S. source income.
For example, if a Canadian does not have U.S. source income and donates to a U.S. charity, no deduction is available. If a Canadian has $10,000 in U.S. source income and donates $1,000 to a U.S. charity, the contribution may be fully deductible, since he/she has U.S. source income, and the amount contributed is less than $7,500. Consult with an accountant or the Canada Revenue Agency for more information.