No, unless I have been harbouring a misconception for the past 13 years. When you are talking about a tax credit, be it refundable or not, or some type of exemption or reduction, according to the federal Income Tax Act, an agreement with the provinces is not required. There is some harmonization, for example, between the provinces and the federal government when measures are implemented in an effort to facilitate fiscal management. However, in the case of a refundable tax credit decreed by the federal government, no arrangement is necessary.
On May 30th, 2006. See this statement in context.